kernel/linux.git/drivers/target/target_core_user.c, branch v6.12.80

genetlink: hold RCU in genlmsg_mcast()

2024-10-16T00:52:58+00:00

While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw one lockdep splat [1]. genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU. Instead of letting all callers guard genlmsg_multicast_allns() with a rcu_read_lock()/rcu_read_unlock() pair, do it in genlmsg_mcast(). This also means the @flags parameter is useless, we need to always use GFP_ATOMIC. [1] [10882.424136] ============================= [10882.424166] WARNING: suspicious RCU usage [10882.424309] 6.12.0-rc2-virtme #1156 Not tainted [10882.424400] ----------------------------- [10882.424423] net/netlink/genetlink.c:1940 RCU-list traversed in non-reader section!! [10882.424469] other info that might help us debug this: [10882.424500] rcu_scheduler_active = 2, debug_locks = 1 [10882.424744] 2 locks held by ip/15677: [10882.424791] #0: ffffffffb6b491b0 (cb_lock){++++}-{3:3}, at: genl_rcv (net/netlink/genetlink.c:1219) [10882.426334] #1: ffffffffb6b49248 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg (net/netlink/genetlink.c:61 net/netlink/genetlink.c:57 net/netlink/genetlink.c:1209) [10882.426465] stack backtrace: [10882.426805] CPU: 14 UID: 0 PID: 15677 Comm: ip Not tainted 6.12.0-rc2-virtme #1156 [10882.426919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [10882.427046] Call Trace: [10882.427131] [10882.427244] dump_stack_lvl (lib/dump_stack.c:123) [10882.427335] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822) [10882.427387] genlmsg_multicast_allns (net/netlink/genetlink.c:1940 (discriminator 7) net/netlink/genetlink.c:1977 (discriminator 7)) [10882.427436] l2tp_tunnel_notify.constprop.0 (net/l2tp/l2tp_netlink.c:119) l2tp_netlink [10882.427683] l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:253) l2tp_netlink [10882.427748] genl_family_rcv_msg_doit (net/netlink/genetlink.c:1115) [10882.427834] genl_rcv_msg (net/netlink/genetlink.c:1195 net/netlink/genetlink.c:1210) [10882.427877] ? __pfx_l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:186) l2tp_netlink [10882.427927] ? __pfx_genl_rcv_msg (net/netlink/genetlink.c:1201) [10882.427959] netlink_rcv_skb (net/netlink/af_netlink.c:2551) [10882.428069] genl_rcv (net/netlink/genetlink.c:1220) [10882.428095] netlink_unicast (net/netlink/af_netlink.c:1332 net/netlink/af_netlink.c:1357) [10882.428140] netlink_sendmsg (net/netlink/af_netlink.c:1901) [10882.428210] ____sys_sendmsg (net/socket.c:729 (discriminator 1) net/socket.c:744 (discriminator 1) net/socket.c:2607 (discriminator 1)) Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners") Signed-off-by: Eric Dumazet Cc: James Chapman Cc: Tom Parkin Cc: Johannes Berg Link: https://patch.msgid.link/20241011171217.3166614-1-edumazet@google.com Signed-off-by: Jakub Kicinski

scsi: target: tcmu: Annotate struct tcmu_tmr with __counted_by

2023-09-27T15:28:48+00:00

Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). As found with Coccinelle[1], add __counted_by for struct tcmu_tmr. [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci Cc: Bodo Stroesser Cc: "Martin K. Petersen" Cc: linux-scsi@vger.kernel.org Cc: target-devel@vger.kernel.org Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20230922175300.work.148-kees@kernel.org Reviewed-by: "Gustavo A. R. Silva" Reviewed-by: Bodo Stroesser Signed-off-by: Martin K. Petersen

scsi: target: tcmu: Replace strlcpy() with strscpy()

2023-06-22T01:13:00+00:00

strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated [1]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). No return values were used, so direct replacement is safe. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh Link: https://lore.kernel.org/r/20230621030033.3800351-3-azeemshaikh38@gmail.com Reviewed-by: Kees Cook Signed-off-by: Martin K. Petersen

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39+00:00

Replace direct modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. [akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo] Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Acked-by: Mel Gorman Acked-by: Mike Rapoport (IBM) Acked-by: Sebastian Reichel Reviewed-by: Liam R. Howlett Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Andy Lutomirski Cc: Arjun Roy Cc: Axel Rasmussen Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Thelen Cc: Hugh Dickins Cc: Ingo Molnar Cc: Jann Horn Cc: Joel Fernandes Cc: Johannes Weiner Cc: Kent Overstreet Cc: Laurent Dufour Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Minchan Kim Cc: Paul E. McKenney Cc: Peter Oskolkov Cc: Peter Xu Cc: Peter Zijlstra Cc: Punit Agrawal Cc: Sebastian Andrzej Siewior Cc: Shakeel Butt Cc: Soheil Hassas Yeganeh Cc: Song Liu Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

genetlink: start to validate reserved header bytes

2022-08-29T11:47:15+00:00

We had historically not checked that genlmsghdr.reserved is 0 on input which prevents us from using those precious bytes in the future. One use case would be to extend the cmd field, which is currently just 8 bits wide and 256 is not a lot of commands for some core families. To make sure that new families do the right thing by default put the onus of opting out of validation on existing families. Signed-off-by: Jakub Kicinski Acked-by: Paul Moore (NetLabel) Signed-off-by: David S. Miller

scsi: target: tcmu: Avoid holding XArray lock when calling lock_page

2022-05-20T00:16:27+00:00

In tcmu_blocks_release(), lock_page() is called to prevent a race causing possible data corruption. Since lock_page() might sleep, calling it while holding XArray lock is a bug. To fix this, replace the xas_for_each() call with xa_for_each_range(). Since the latter does its own handling of XArray locking, the xas_lock() and xas_unlock() calls around the original loop are no longer necessary. The switch to xa_for_each_range() slows down the loop slightly. This is acceptable since tcmu_blocks_release() is not relevant for performance. Link: https://lore.kernel.org/r/20220517192913.21405-1-bostroesser@gmail.com Fixes: bb9b9eb0ae2e ("scsi: target: tcmu: Fix possible data corruption") Reported-by: Dan Carpenter Signed-off-by: Bodo Stroesser Signed-off-by: Martin K. Petersen

scsi: target: tcmu: Fix possible data corruption

2022-05-02T20:59:11+00:00

When tcmu_vma_fault() gets a page successfully, before the current context completes page fault procedure, find_free_blocks() may run and call unmap_mapping_range() to unmap the page. Assume that when find_free_blocks() initially completes and the previous page fault procedure starts to run again and completes, then one truncated page has been mapped to userspace. But note that tcmu_vma_fault() has gotten a refcount for the page so any other subsystem won't be able to use the page unless the userspace address is unmapped later. If another command subsequently runs and needs to extend dbi_thresh it may reuse the corresponding slot for the previous page in data_bitmap. Then though we'll allocate new page for this slot in data_area, no page fault will happen because we have a valid map and the real request's data will be lost. Filesystem implementations will also run into this issue but they usually lock the page when vm_operations_struct->fault gets a page and unlock the page after finish_fault() completes. For truncate filesystems lock pages in truncate_inode_pages() to protect against racing wrt. page faults. To fix this possible data corruption scenario we can apply a method similar to the filesystems. For pages that are to be freed, tcmu_blocks_release() locks and unlocks. Make tcmu_vma_fault() also lock found page under cmdr_lock. At the same time, since tcmu_vma_fault() gets an extra page refcount, tcmu_blocks_release() won't free pages if pages are in page fault procedure, which means it is safe to call tcmu_blocks_release() before unmap_mapping_range(). With these changes tcmu_blocks_release() will wait for all page faults to be completed before calling unmap_mapping_range(). And later, if unmap_mapping_range() is called, it will ensure stale mappings are removed. Link: https://lore.kernel.org/r/20220421023735.9018-1-xiaoguang.wang@linux.alibaba.com Reviewed-by: Bodo Stroesser Signed-off-by: Xiaoguang Wang Signed-off-by: Martin K. Petersen

scsi: target: tcmu: Fix possible page UAF

2022-03-30T03:07:56+00:00

tcmu_try_get_data_page() looks up pages under cmdr_lock, but it does not take refcount properly and just returns page pointer. When tcmu_try_get_data_page() returns, the returned page may have been freed by tcmu_blocks_release(). We need to get_page() under cmdr_lock to avoid concurrent tcmu_blocks_release(). Link: https://lore.kernel.org/r/20220311132206.24515-1-xiaoguang.wang@linux.alibaba.com Reviewed-by: Bodo Stroesser Signed-off-by: Xiaoguang Wang Signed-off-by: Martin K. Petersen

scsi: target: tcmu: Make cmd_ring_size changeable via configfs

2022-02-23T02:11:07+00:00

Make cmd_ring_size changeable similar to the way it is done for max_data_area_mb. The reason is that our tcmu client will create thousands of tcmu instances, and this will consume lots of mem with default 8Mb cmd ring size for every backstore. One can change the value by typing: echo "cmd_ring_size_mb=N" > control The "N" is a integer between 1 to 8, if set 1, the cmd ring can hold about 6k cmds(tcmu_cmd_entry about 176 byte) at least. The value is printed when doing: cat info In addition, a new readonly attribute 'cmd_ring_size_mb' returns the value in read. Link: https://lore.kernel.org/r/1644978109-14885-1-git-send-email-kanie@linux.alibaba.com Reviewed-by: Xiaoguang Wang Reviewed-by: Bodo Stroesser Signed-off-by: Guixin Liu Signed-off-by: Martin K. Petersen

scsi: target: tcmu: Allocate zeroed pages for data area

2021-10-19T02:38:35+00:00

Tcmu populates the data area (used for communication with userspace) with pages that are allocated by calling alloc_page(GFP_NOIO). Therefore previous content of the allocated pages is exposed to user space. Avoid this by adding __GFP_ZERO flag. Zeroing the pages does (nearly) not affect tcmu throughput, because allocated pages are re-used for the data transfers of later SCSI cmds. Link: https://lore.kernel.org/r/20211013171606.25197-1-bostroesser@gmail.com Signed-off-by: Bodo Stroesser Signed-off-by: Martin K. Petersen