kernel/linux.git/include/linux/list.h, branch v6.6.132

list: Introduce CONFIG_LIST_HARDENED

2023-08-15T21:57:25+00:00

Numerous production kernel configs (see [1, 2]) are choosing to enable CONFIG_DEBUG_LIST, which is also being recommended by KSPP for hardened configs [3]. The motivation behind this is that the option can be used as a security hardening feature (e.g. CVE-2019-2215 and CVE-2019-2025 are mitigated by the option [4]). The feature has never been designed with performance in mind, yet common list manipulation is happening across hot paths all over the kernel. Introduce CONFIG_LIST_HARDENED, which performs list pointer checking inline, and only upon list corruption calls the reporting slow path. To generate optimal machine code with CONFIG_LIST_HARDENED: 1. Elide checking for pointer values which upon dereference would result in an immediate access fault (i.e. minimal hardening checks). The trade-off is lower-quality error reports. 2. Use the __preserve_most function attribute (available with Clang, but not yet with GCC) to minimize the code footprint for calling the reporting slow path. As a result, function size of callers is reduced by avoiding saving registers before calling the rarely called reporting slow path. Note that all TUs in lib/Makefile already disable function tracing, including list_debug.c, and __preserve_most's implied notrace has no effect in this case. 3. Because the inline checks are a subset of the full set of checks in __list_*_valid_or_report(), always return false if the inline checks failed. This avoids redundant compare and conditional branch right after return from the slow path. As a side-effect of the checks being inline, if the compiler can prove some condition to always be true, it can completely elide some checks. Since DEBUG_LIST is functionally a superset of LIST_HARDENED, the Kconfig variables are changed to reflect that: DEBUG_LIST selects LIST_HARDENED, whereas LIST_HARDENED itself has no dependency on DEBUG_LIST. Running netperf with CONFIG_LIST_HARDENED (using a Clang compiler with "preserve_most") shows throughput improvements, in my case of ~7% on average (up to 20-30% on some test cases). Link: https://r.android.com/1266735 [1] Link: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/blob/main/config [2] Link: https://kernsec.org/wiki/index.php/Kernel_Self_Protection_Project/Recommended_Settings [3] Link: https://googleprojectzero.blogspot.com/2019/11/bad-binder-android-in-wild-exploit.html [4] Signed-off-by: Marco Elver Link: https://lore.kernel.org/r/20230811151847.1594958-3-elver@google.com Signed-off-by: Kees Cook

list_debug: Introduce inline wrappers for debug checks

2023-08-15T21:57:24+00:00

Turn the list debug checking functions __list_*_valid() into inline functions that wrap the out-of-line functions. Care is taken to ensure the inline wrappers are always inlined, so that additional compiler instrumentation (such as sanitizers) does not result in redundant outlining. This change is preparation for performing checks in the inline wrappers. No functional change intended. Signed-off-by: Marco Elver Link: https://lore.kernel.org/r/20230811151847.1594958-2-elver@google.com Signed-off-by: Kees Cook

i915: Move list_count() to list.h as list_count_nodes() for broader use

2023-01-06T15:37:46+00:00

Some of the existing users, and definitely will be new ones, want to count existing nodes in the list. Provide a generic API for that by moving code from i915 to list.h. Reviewed-by: Lucas De Marchi Acked-by: Jani Nikula Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20221130134838.23805-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

Merge tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-05-27T18:22:03+00:00

Pull misc updates from Andrew Morton: "The non-MM patch queue for this merge window. Not a lot of material this cycle. Many singleton patches against various subsystems. Most notably some maintenance work in ocfs2 and initramfs" * tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (65 commits) kcov: update pos before writing pc in trace function ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock fs/ntfs: remove redundant variable idx fat: remove time truncations in vfat_create/vfat_mkdir fat: report creation time in statx fat: ignore ctime updates, and keep ctime identical to mtime in memory fat: split fat_truncate_time() into separate functions MAINTAINERS: add Muchun as a memcg reviewer proc/sysctl: make protected_* world readable ia64: mca: drop redundant spinlock initialization tty: fix deadlock caused by calling printk() under tty_port->lock relay: remove redundant assignment to pointer buf fs/ntfs3: validate BOOT sectors_per_clusters lib/string_helpers: fix not adding strarray to device's resource list kernel/crash_core.c: remove redundant check of ck_cmdline ELF, uapi: fixup ELF_ST_TYPE definition ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() ipc: update semtimedop() to use hrtimer ipc/sem: remove redundant assignments ...

rxrpc: Fix locking issue

2022-05-22T20:03:01+00:00

There's a locking issue with the per-netns list of calls in rxrpc. The pieces of code that add and remove a call from the list use write_lock() and the calls procfile uses read_lock() to access it. However, the timer callback function may trigger a removal by trying to queue a call for processing and finding that it's already queued - at which point it has a spare refcount that it has to do something with. Unfortunately, if it puts the call and this reduces the refcount to 0, the call will be removed from the list. Unfortunately, since the _bh variants of the locking functions aren't used, this can deadlock. ================================ WARNING: inconsistent lock state 5.18.0-rc3-build4+ #10 Not tainted -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. ksoftirqd/2/25 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff888107ac4038 (&rxnet->call_lock){+.?.}-{2:2}, at: rxrpc_put_call+0x103/0x14b {SOFTIRQ-ON-W} state was registered at: ... Possible unsafe locking scenario: CPU0 ---- lock(&rxnet->call_lock); lock(&rxnet->call_lock); *** DEADLOCK *** 1 lock held by ksoftirqd/2/25: #0: ffff8881008ffdb0 ((&call->timer)){+.-.}-{0:0}, at: call_timer_fn+0x5/0x23d Changes ======= ver #2) - Changed to using list_next_rcu() rather than rcu_dereference() directly. Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Signed-off-by: David Howells cc: Marc Dionne cc: linux-afs@lists.infradead.org Signed-off-by: David S. Miller

list: Add list_next_entry_circular() and list_prev_entry_circular()

2022-05-09T09:51:58+00:00

Add macros to get the next or previous entries and wraparound if needed. For example, calling list_next_entry_circular() on the last element should return the first element in the list. Signed-off-by: Ricardo Martinez Reviewed-by: Andy Shevchenko Signed-off-by: David S. Miller

list: fix a data-race around ep->rdllist

2022-04-29T21:38:01+00:00

ep_poll() first calls ep_events_available() with no lock held and checks if ep->rdllist is empty by list_empty_careful(), which reads rdllist->prev. Thus all accesses to it need some protection to avoid store/load-tearing. Note INIT_LIST_HEAD_RCU() already has the annotation for both prev and next. Commit bf3b9f6372c4 ("epoll: Add busy poll support to epoll with socket fds.") added the first lockless ep_events_available(), and commit c5a282e9635e ("fs/epoll: reduce the scope of wq lock in epoll_wait()") made some ep_events_available() calls lockless and added single call under a lock, finally commit e59d3c64cba6 ("epoll: eliminate unnecessary lock for zero timeout") made the last ep_events_available() lockless. BUG: KCSAN: data-race in do_epoll_wait / do_epoll_wait write to 0xffff88810480c7d8 of 8 bytes by task 1802 on cpu 0: INIT_LIST_HEAD include/linux/list.h:38 [inline] list_splice_init include/linux/list.h:492 [inline] ep_start_scan fs/eventpoll.c:622 [inline] ep_send_events fs/eventpoll.c:1656 [inline] ep_poll fs/eventpoll.c:1806 [inline] do_epoll_wait+0x4eb/0xf40 fs/eventpoll.c:2234 do_epoll_pwait fs/eventpoll.c:2268 [inline] __do_sys_epoll_pwait fs/eventpoll.c:2281 [inline] __se_sys_epoll_pwait+0x12b/0x240 fs/eventpoll.c:2275 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2275 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff88810480c7d8 of 8 bytes by task 1799 on cpu 1: list_empty_careful include/linux/list.h:329 [inline] ep_events_available fs/eventpoll.c:381 [inline] ep_poll fs/eventpoll.c:1797 [inline] do_epoll_wait+0x279/0xf40 fs/eventpoll.c:2234 do_epoll_pwait fs/eventpoll.c:2268 [inline] __do_sys_epoll_pwait fs/eventpoll.c:2281 [inline] __se_sys_epoll_pwait+0x12b/0x240 fs/eventpoll.c:2275 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2275 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0xffff88810480c7d0 -> 0xffff888103c15098 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 1799 Comm: syz-fuzzer Tainted: G W 5.17.0-rc7-syzkaller-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Link: https://lkml.kernel.org/r/20220322002653.33865-3-kuniyu@amazon.co.jp Fixes: e59d3c64cba6 ("epoll: eliminate unnecessary lock for zero timeout") Fixes: c5a282e9635e ("fs/epoll: reduce the scope of wq lock in epoll_wait()") Fixes: bf3b9f6372c4 ("epoll: Add busy poll support to epoll with socket fds.") Signed-off-by: Kuniyuki Iwashima Reported-by: syzbot+bdd6e38a1ed5ee58d8bd@syzkaller.appspotmail.com Cc: Al Viro , Andrew Morton Cc: Kuniyuki Iwashima Cc: Kuniyuki Iwashima Cc: "Soheil Hassas Yeganeh" Cc: Davidlohr Bueso Cc: "Sridhar Samudrala" Cc: Alexander Duyck Signed-off-by: Andrew Morton

list: introduce list_is_head() helper and re-use it in list.h

2022-01-20T06:52:53+00:00

Introduce list_is_head() in the similar (*) way as it's done for list_entry_is_head(). Make use of it in the list.h. *) it's done as inliner and not a macro to be aligned with other list_is_*() APIs; while at it, make all three to have the same style. Link: https://lkml.kernel.org/r/20211201141824.81400-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Cc: Heikki Krogerus Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

include/linux/list.h: replace kernel.h with the necessary inclusions

2021-11-09T18:02:49+00:00

When kernel.h is used in the headers it adds a lot into dependency hell, especially when there are circular dependencies are involved. Replace kernel.h inclusion with the list of what is really being used. Link: https://lkml.kernel.org/r/20211013170417.87909-5-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Cc: Boqun Feng Cc: Brendan Higgins Cc: Ingo Molnar Cc: Jonathan Cameron Cc: Laurent Pinchart Cc: Mauro Carvalho Chehab Cc: Miguel Ojeda Cc: Peter Zijlstra Cc: Rasmus Villemoes Cc: Sakari Ailus Cc: Thomas Gleixner Cc: Thorsten Leemhuis Cc: Waiman Long Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

list: Fix a typo at the kernel-doc markup

2021-01-04T21:35:14+00:00

hlist_add_behing -> hlist_add_behind Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Paul E. McKenney