kernel/linux.git/drivers/net/ppp, branch v4.19.16

pppoe: fix reception of frames with no mac header

2018-09-17T14:50:26+00:00

pppoe_rcv() needs to look back at the Ethernet header in order to lookup the PPPoE session. Therefore we need to ensure that the mac header is big enough to contain an Ethernet header. Otherwise eth_hdr(skb)->h_source might access invalid data. ================================================================== BUG: KMSAN: uninit-value in __get_item drivers/net/ppp/pppoe.c:172 [inline] BUG: KMSAN: uninit-value in get_item drivers/net/ppp/pppoe.c:236 [inline] BUG: KMSAN: uninit-value in pppoe_rcv+0xcef/0x10e0 drivers/net/ppp/pppoe.c:450 CPU: 0 PID: 4543 Comm: syz-executor355 Not tainted 4.16.0+ #87 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x185/0x1d0 lib/dump_stack.c:53 kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1067 __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683 __get_item drivers/net/ppp/pppoe.c:172 [inline] get_item drivers/net/ppp/pppoe.c:236 [inline] pppoe_rcv+0xcef/0x10e0 drivers/net/ppp/pppoe.c:450 __netif_receive_skb_core+0x47df/0x4a90 net/core/dev.c:4562 __netif_receive_skb net/core/dev.c:4627 [inline] netif_receive_skb_internal+0x49d/0x630 net/core/dev.c:4701 netif_receive_skb+0x230/0x240 net/core/dev.c:4725 tun_rx_batched drivers/net/tun.c:1555 [inline] tun_get_user+0x740f/0x7c60 drivers/net/tun.c:1962 tun_chr_write_iter+0x1d4/0x330 drivers/net/tun.c:1990 call_write_iter include/linux/fs.h:1782 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x7fb/0x9f0 fs/read_write.c:482 vfs_write+0x463/0x8d0 fs/read_write.c:544 SYSC_write+0x172/0x360 fs/read_write.c:589 SyS_write+0x55/0x80 fs/read_write.c:581 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x4447c9 RSP: 002b:00007fff64c8fc28 EFLAGS: 00000297 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004447c9 RDX: 000000000000fd87 RSI: 0000000020000600 RDI: 0000000000000004 RBP: 00000000006cf018 R08: 00007fff64c8fda8 R09: 00007fff00006bda R10: 0000000000005fe7 R11: 0000000000000297 R12: 00000000004020d0 R13: 0000000000402160 R14: 0000000000000000 R15: 0000000000000000 Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:278 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:188 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:314 kmsan_slab_alloc+0x11/0x20 mm/kmsan/kmsan.c:321 slab_post_alloc_hook mm/slab.h:445 [inline] slab_alloc_node mm/slub.c:2737 [inline] __kmalloc_node_track_caller+0xaed/0x11c0 mm/slub.c:4369 __kmalloc_reserve net/core/skbuff.c:138 [inline] __alloc_skb+0x2cf/0x9f0 net/core/skbuff.c:206 alloc_skb include/linux/skbuff.h:984 [inline] alloc_skb_with_frags+0x1d4/0xb20 net/core/skbuff.c:5234 sock_alloc_send_pskb+0xb56/0x1190 net/core/sock.c:2085 tun_alloc_skb drivers/net/tun.c:1532 [inline] tun_get_user+0x2242/0x7c60 drivers/net/tun.c:1829 tun_chr_write_iter+0x1d4/0x330 drivers/net/tun.c:1990 call_write_iter include/linux/fs.h:1782 [inline] new_sync_write fs/read_write.c:469 [inline] __vfs_write+0x7fb/0x9f0 fs/read_write.c:482 vfs_write+0x463/0x8d0 fs/read_write.c:544 SYSC_write+0x172/0x360 fs/read_write.c:589 SyS_write+0x55/0x80 fs/read_write.c:581 do_syscall_64+0x309/0x430 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 ================================================================== Fixes: 224cf5ad14c0 ("ppp: Move the PPP drivers") Reported-by: syzbot+f5f6080811c849739212@syzkaller.appspotmail.com Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller

ppp: mppe: Remove VLA usage

2018-08-03T19:54:54+00:00

In the quest to remove all stack VLA usage from the kernel[1], this removes the discouraged use of AHASH_REQUEST_ON_STACK (and associated VLA) by switching to shash directly and keeping the associated descriptor allocated with the regular state on the heap. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook Acked-by: Arnd Bergmann Signed-off-by: David S. Miller

Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL

2018-06-28T17:40:47+00:00

The poll() changes were not well thought out, and completely unexplained. They also caused a huge performance regression, because "->poll()" was no longer a trivial file operation that just called down to the underlying file operations, but instead did at least two indirect calls. Indirect calls are sadly slow now with the Spectre mitigation, but the performance problem could at least be largely mitigated by changing the "->get_poll_head()" operation to just have a per-file-descriptor pointer to the poll head instead. That gets rid of one of the new indirections. But that doesn't fix the new complexity that is completely unwarranted for the regular case. The (undocumented) reason for the poll() changes was some alleged AIO poll race fixing, but we don't make the common case slower and more complex for some uncommon special case, so this all really needs way more explanations and most likely a fundamental redesign. [ This revert is a revert of about 30 different commits, not reverted individually because that would just be unnecessarily messy - Linus ] Cc: Al Viro Cc: Christoph Hellwig Signed-off-by: Linus Torvalds

treewide: Use array_size() in vzalloc()

2018-06-12T23:19:22+00:00

The vzalloc() function has no 2-factor argument form, so multiplication factors need to be wrapped in array_size(). This patch replaces cases of: vzalloc(a * b) with: vzalloc(array_size(a, b)) as well as handling cases of: vzalloc(a * b * c) with: vzalloc(array3_size(a, b, c)) This does, however, attempt to ignore constant size factors like: vzalloc(4 * 1024) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( vzalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | vzalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( vzalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | vzalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | vzalloc( - sizeof(char) * (COUNT) + COUNT , ...) | vzalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | vzalloc( - sizeof(u8) * COUNT + COUNT , ...) | vzalloc( - sizeof(__u8) * COUNT + COUNT , ...) | vzalloc( - sizeof(char) * COUNT + COUNT , ...) | vzalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( vzalloc( - sizeof(TYPE) * (COUNT_ID) + array_size(COUNT_ID, sizeof(TYPE)) , ...) | vzalloc( - sizeof(TYPE) * COUNT_ID + array_size(COUNT_ID, sizeof(TYPE)) , ...) | vzalloc( - sizeof(TYPE) * (COUNT_CONST) + array_size(COUNT_CONST, sizeof(TYPE)) , ...) | vzalloc( - sizeof(TYPE) * COUNT_CONST + array_size(COUNT_CONST, sizeof(TYPE)) , ...) | vzalloc( - sizeof(THING) * (COUNT_ID) + array_size(COUNT_ID, sizeof(THING)) , ...) | vzalloc( - sizeof(THING) * COUNT_ID + array_size(COUNT_ID, sizeof(THING)) , ...) | vzalloc( - sizeof(THING) * (COUNT_CONST) + array_size(COUNT_CONST, sizeof(THING)) , ...) | vzalloc( - sizeof(THING) * COUNT_CONST + array_size(COUNT_CONST, sizeof(THING)) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ vzalloc( - SIZE * COUNT + array_size(COUNT, SIZE) , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( vzalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vzalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vzalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vzalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vzalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | vzalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | vzalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | vzalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( vzalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | vzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | vzalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | vzalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | vzalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | vzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( vzalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vzalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( vzalloc(C1 * C2 * C3, ...) | vzalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants. @@ expression E1, E2; constant C1, C2; @@ ( vzalloc(C1 * C2, ...) | vzalloc( - E1 * E2 + array_size(E1, E2) , ...) ) Signed-off-by: Kees Cook

treewide: Use array_size() in vmalloc()

2018-06-12T23:19:22+00:00

The vmalloc() function has no 2-factor argument form, so multiplication factors need to be wrapped in array_size(). This patch replaces cases of: vmalloc(a * b) with: vmalloc(array_size(a, b)) as well as handling cases of: vmalloc(a * b * c) with: vmalloc(array3_size(a, b, c)) This does, however, attempt to ignore constant size factors like: vmalloc(4 * 1024) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( vmalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | vmalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( vmalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | vmalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | vmalloc( - sizeof(char) * (COUNT) + COUNT , ...) | vmalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | vmalloc( - sizeof(u8) * COUNT + COUNT , ...) | vmalloc( - sizeof(__u8) * COUNT + COUNT , ...) | vmalloc( - sizeof(char) * COUNT + COUNT , ...) | vmalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( vmalloc( - sizeof(TYPE) * (COUNT_ID) + array_size(COUNT_ID, sizeof(TYPE)) , ...) | vmalloc( - sizeof(TYPE) * COUNT_ID + array_size(COUNT_ID, sizeof(TYPE)) , ...) | vmalloc( - sizeof(TYPE) * (COUNT_CONST) + array_size(COUNT_CONST, sizeof(TYPE)) , ...) | vmalloc( - sizeof(TYPE) * COUNT_CONST + array_size(COUNT_CONST, sizeof(TYPE)) , ...) | vmalloc( - sizeof(THING) * (COUNT_ID) + array_size(COUNT_ID, sizeof(THING)) , ...) | vmalloc( - sizeof(THING) * COUNT_ID + array_size(COUNT_ID, sizeof(THING)) , ...) | vmalloc( - sizeof(THING) * (COUNT_CONST) + array_size(COUNT_CONST, sizeof(THING)) , ...) | vmalloc( - sizeof(THING) * COUNT_CONST + array_size(COUNT_CONST, sizeof(THING)) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ vmalloc( - SIZE * COUNT + array_size(COUNT, SIZE) , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( vmalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vmalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vmalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vmalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | vmalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | vmalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | vmalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | vmalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( vmalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | vmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | vmalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | vmalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | vmalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | vmalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( vmalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | vmalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( vmalloc(C1 * C2 * C3, ...) | vmalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants. @@ expression E1, E2; constant C1, C2; @@ ( vmalloc(C1 * C2, ...) | vmalloc( - E1 * E2 + array_size(E1, E2) , ...) ) Signed-off-by: Kees Cook

Merge branch 'work.aio-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2018-06-04T20:57:43+00:00

Pull aio updates from Al Viro: "Majority of AIO stuff this cycle. aio-fsync and aio-poll, mostly. The only thing I'm holding back for a day or so is Adam's aio ioprio - his last-minute fixup is trivial (missing stub in !CONFIG_BLOCK case), but let it sit in -next for decency sake..." * 'work.aio-1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (46 commits) aio: sanitize the limit checking in io_submit(2) aio: fold do_io_submit() into callers aio: shift copyin of iocb into io_submit_one() aio_read_events_ring(): make a bit more readable aio: all callers of aio_{read,write,fsync,poll} treat 0 and -EIOCBQUEUED the same way aio: take list removal to (some) callers of aio_complete() aio: add missing break for the IOCB_CMD_FDSYNC case random: convert to ->poll_mask timerfd: convert to ->poll_mask eventfd: switch to ->poll_mask pipe: convert to ->poll_mask crypto: af_alg: convert to ->poll_mask net/rxrpc: convert to ->poll_mask net/iucv: convert to ->poll_mask net/phonet: convert to ->poll_mask net/nfc: convert to ->poll_mask net/caif: convert to ->poll_mask net/bluetooth: convert to ->poll_mask net/sctp: convert to ->poll_mask net/tipc: convert to ->poll_mask ...

Merge branch 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2018-06-04T17:00:01+00:00

Pull procfs updates from Al Viro: "Christoph's proc_create_... cleanups series" * 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (44 commits) xfs, proc: hide unused xfs procfs helpers isdn/gigaset: add back gigaset_procinfo assignment proc: update SIZEOF_PDE_INLINE_NAME for the new pde fields tty: replace ->proc_fops with ->proc_show ide: replace ->proc_fops with ->proc_show ide: remove ide_driver_proc_write isdn: replace ->proc_fops with ->proc_show atm: switch to proc_create_seq_private atm: simplify procfs code bluetooth: switch to proc_create_seq_data netfilter/x_tables: switch to proc_create_seq_private netfilter/xt_hashlimit: switch to proc_create_{seq,single}_data neigh: switch to proc_create_seq_data hostap: switch to proc_create_{seq,single}_data bonding: switch to proc_create_seq_data rtc/proc: switch to proc_create_single_data drbd: switch to proc_create_single resource: switch to proc_create_seq_data staging/rtl8192u: simplify procfs code jfs: simplify procfs code ...

net: convert datagram_poll users tp ->poll_mask

2018-05-26T07:16:44+00:00

Signed-off-by: Christoph Hellwig Reviewed-by: Greg Kroah-Hartman

net: remove sock_no_poll

2018-05-26T07:16:44+00:00

Now that sock_poll handles a NULL ->poll or ->poll_mask there is no need for a stub. Signed-off-by: Christoph Hellwig

ppp: remove the PPPIOCDETACH ioctl

2018-05-25T02:55:07+00:00

The PPPIOCDETACH ioctl effectively tries to "close" the given ppp file before f_count has reached 0, which is fundamentally a bad idea. It does check 'f_count < 2', which excludes concurrent operations on the file since they would only be possible with a shared fd table, in which case each fdget() would take a file reference. However, it fails to account for the fact that even with 'f_count == 1' the file can still be linked into epoll instances. As reported by syzbot, this can trivially be used to cause a use-after-free. Yet, the only known user of PPPIOCDETACH is pppd versions older than ppp-2.4.2, which was released almost 15 years ago (November 2003). Also, PPPIOCDETACH apparently stopped working reliably at around the same time, when the f_count check was added to the kernel, e.g. see https://lkml.org/lkml/2002/12/31/83. Also, the current 'f_count < 2' check makes PPPIOCDETACH only work in single-threaded applications; it always fails if called from a multithreaded application. All pppd versions released in the last 15 years just close() the file descriptor instead. Therefore, instead of hacking around this bug by exporting epoll internals to modules, and probably missing other related bugs, just remove the PPPIOCDETACH ioctl and see if anyone actually notices. Leave a stub in place that prints a one-time warning and returns EINVAL. Reported-by: syzbot+16363c99d4134717c05b@syzkaller.appspotmail.com Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers Acked-by: Paul Mackerras Reviewed-by: Guillaume Nault Tested-by: Guillaume Nault Signed-off-by: David S. Miller