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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730859096; bh=qtE7U/TO5/+WKthJmY8uM8QvckXMmynLoyhgpBv+MMA=; h=From:To:Cc:Subject:Date:From; b=IGxbKw9sbID+U857lDW7BJEDTK5YM68HZOSUytItmCIXijYIrwtDmkovSK7fi69tf /9Zkm/8KIrzyiuuntPQksbWTjxe9q6MCqrOrYla3tIxEuPeAKj3+I5zI8kJ4KUr/m6 PCPKXQsCpvhHHx+Cq321aTqhSDi98ErwRB+3AEDtFnTPrPzW0lI/lJyOTj7+EGBUg1 ye3NwtI0JFJmHaNb+4FLoYPivM6ruHORpovCzRkekva/bNJ/UsppYAcTLoMpEHoSFI xj2FQEaBJcJEZJezWNXp/95L8zFK42IkjdRcmVtrWtihFVcMAG21j0UI0rrlKQmiMl pNSWZpsxl41Fw== From: Sasha Levin To: stable@vger.kernel.org, aha310510@gmail.com Cc: syzbot , Hugh Dickins , Yu Zhao , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: FAILED: Patch "mm: shmem: fix data-race in shmem_getattr()" failed to apply to v5.15-stable tree Date: Tue, 5 Nov 2024 21:11:32 -0500 Message-ID: <20241106021133.182288-1-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 X-Patchwork-Hint: ignore X-stable: review Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: A7590A0003 X-Stat-Signature: q6or6z9n7ukwapiq33nu6k5i9kraprf9 X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1730859072-592235 X-HE-Meta: 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 mTC4RDkJ WFP+NDDx3PvVUUjAQHBieGGWtuAotpJ/ylTmtSL2Ich1ZHFvPzYN1S8aUYkR9FnHBtP7pEdoSeh+vyELCKJQd03bi9nChnoHHsz/5lv0jvzSYkyW4GaW07W6klNSCJrsrKdglJ3aCn2uJ48xsD41IaO1J2SE6W9Qm8teHVivb9ZoUtox1NL2pzG/+PVDdL/Pnmwk/gye8DT7E7bNgNv4qbRjeDNGJTI6cwmDdMvQpARw83ejW1P+yihNXX2mGG4d9o2px9ftSliFhWTLxxvKd2AsTFCDM+WNQB0y7HVCWseY5Khrbs2SPHrNP48BeExzWQSh1Pgsym6Sgyd/Y4KFaBWdh0miDXtMGB+arKa0fFDbUntcTxwO2HBxATTQsjRrizkgmw8q1wkvB6vaYazmQGTzUO0UDhGtAxazSPvnnkMLYkPBdHMieetEFzYdS5vMuoR4N X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The patch below does not apply to the v5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From d949d1d14fa281ace388b1de978e8f2cd52875cf Mon Sep 17 00:00:00 2001 From: Jeongjun Park Date: Mon, 9 Sep 2024 21:35:58 +0900 Subject: [PATCH] mm: shmem: fix data-race in shmem_getattr() I got the following KCSAN report during syzbot testing: ================================================================== BUG: KCSAN: data-race in generic_fillattr / inode_set_ctime_current write to 0xffff888102eb3260 of 4 bytes by task 6565 on cpu 1: inode_set_ctime_to_ts include/linux/fs.h:1638 [inline] inode_set_ctime_current+0x169/0x1d0 fs/inode.c:2626 shmem_mknod+0x117/0x180 mm/shmem.c:3443 shmem_create+0x34/0x40 mm/shmem.c:3497 lookup_open fs/namei.c:3578 [inline] open_last_lookups fs/namei.c:3647 [inline] path_openat+0xdbc/0x1f00 fs/namei.c:3883 do_filp_open+0xf7/0x200 fs/namei.c:3913 do_sys_openat2+0xab/0x120 fs/open.c:1416 do_sys_open fs/open.c:1431 [inline] __do_sys_openat fs/open.c:1447 [inline] __se_sys_openat fs/open.c:1442 [inline] __x64_sys_openat+0xf3/0x120 fs/open.c:1442 x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x76/0x7e read to 0xffff888102eb3260 of 4 bytes by task 3498 on cpu 0: inode_get_ctime_nsec include/linux/fs.h:1623 [inline] inode_get_ctime include/linux/fs.h:1629 [inline] generic_fillattr+0x1dd/0x2f0 fs/stat.c:62 shmem_getattr+0x17b/0x200 mm/shmem.c:1157 vfs_getattr_nosec fs/stat.c:166 [inline] vfs_getattr+0x19b/0x1e0 fs/stat.c:207 vfs_statx_path fs/stat.c:251 [inline] vfs_statx+0x134/0x2f0 fs/stat.c:315 vfs_fstatat+0xec/0x110 fs/stat.c:341 __do_sys_newfstatat fs/stat.c:505 [inline] __se_sys_newfstatat+0x58/0x260 fs/stat.c:499 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:499 x64_sys_call+0x141f/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:263 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x76/0x7e value changed: 0x2755ae53 -> 0x27ee44d3 Reported by Kernel Concurrency Sanitizer on: CPU: 0 UID: 0 PID: 3498 Comm: udevd Not tainted 6.11.0-rc6-syzkaller-00326-gd1f2d51b711a-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 ================================================================== When calling generic_fillattr(), if you don't hold read lock, data-race will occur in inode member variables, which can cause unexpected behavior. Since there is no special protection when shmem_getattr() calls generic_fillattr(), data-race occurs by functions such as shmem_unlink() or shmem_mknod(). This can cause unexpected results, so commenting it out is not enough. Therefore, when calling generic_fillattr() from shmem_getattr(), it is appropriate to protect the inode using inode_lock_shared() and inode_unlock_shared() to prevent data-race. Link: https://lkml.kernel.org/r/20240909123558.70229-1-aha310510@gmail.com Fixes: 44a30220bc0a ("shmem: recalculate file inode when fstat") Signed-off-by: Jeongjun Park Reported-by: syzbot Cc: Hugh Dickins Cc: Yu Zhao Cc: Signed-off-by: Andrew Morton --- mm/shmem.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index c5adb987b23cf..4ba1d00fabdaa 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1166,7 +1166,9 @@ static int shmem_getattr(struct mnt_idmap *idmap, stat->attributes_mask |= (STATX_ATTR_APPEND | STATX_ATTR_IMMUTABLE | STATX_ATTR_NODUMP); + inode_lock_shared(inode); generic_fillattr(idmap, request_mask, inode, stat); + inode_unlock_shared(inode); if (shmem_huge_global_enabled(inode, 0, 0, false, NULL, 0)) stat->blksize = HPAGE_PMD_SIZE; -- 2.43.0