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b=ZF7h8UoJfA2o26X3cjyt4HlQL2Z2GM0awubZdc4952Ge+vekZ8faJBVVt9hA8jg24 DpWCGrl4MzlAA8YPve/xTPFOEmTVZwEojxkeNBESwnQSkUmeZI8/7slKYoq5QP6CS6 inHUqFgGYatfQyf7WxHT7qfywnSLjKQ7Ml+E7CiivdEXuCzOwGkjSjDAtOYfAXCkde cMVEcwS7DnTlmgYhfYlEpOV+yHZ3yB3Q9ktECUGB4aN7JIacgfrSrMuX5AMSV+rabL K+x5y16LPmD0+gfkhuwe84C/b55cTa5VrayxM7L0CmmQfeiz+jcJ57kY7R5JMJDZwB 6EbJx/Gl/khJA== 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 v5.10-stable tree Date: Tue, 5 Nov 2024 21:12:27 -0500 Message-ID: <20241106021227.182927-1-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-Stat-Signature: dnwq37g1nxdwmbn7ugcuz88r7qybh8z5 X-Rspam-User: X-Rspamd-Queue-Id: 46209100013 X-Rspamd-Server: rspam02 X-HE-Tag: 1730859088-454358 X-HE-Meta: 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 mb9Oyjd1 6v9Jb2TNxNSPoqFrYNewiMatHAqiT00APre7ltIpS9QYIPIMe+TVIbZb8tC63+XxfEgPu23IYczGRZn2ThyE4WqrDSwjEJoKo4TD869MG1djFOgpNNdOLZM1WwCA4Mv9udGDUyYYvXiLG/7yNfHhxvzHAhuD2pUY1BkkBCqyfBWe0sbrZOR044k0aA3KXu7ixLN8CA/4sq1Hlu6zodcma4VV8liBo9xqiogKHNxtUt9wqIsLc0E+q2RGyhoWvLUvUHyzsxd7kvFe9cnYiAXt29fSyzSG2eIDKmVYjTyTrJ/pACBIrvmnFMPAR8iVwZaZKHqejuY9KYG2D8BPzuPiautQY/IZrRXftZp3s9KMF9HIrGJSbgdyLIj2AgIVdwtDvBIYqA07TOzn/Yjrt7egKP0zz1rn9vFsnCsmrNk9JK3KDsNw9DPpRkkPNeZxzQVB7ckQN 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 v5.10-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