From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C44F51D89E5 for ; Tue, 5 Nov 2024 16:36:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730824565; cv=none; b=bqtUssw/z6ThuwsXG/gFalxrD7t50XYkLP1467ja9eBvq+cZ/6ZA4B2tlSTTVC6aFlYV1coCeNq8OYVFamIQilH9/ioDSWbqxFTwCP29J+sST2RZNDJnTVI2HRLgRbE5Z4yMBA46dMoC7CeVpyPE5CXCP/JfoI2ae5wmxRQ0tds= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730824565; c=relaxed/simple; bh=FRUBLc9XwIwvwKoViBevKsXG4ZuvaTF1gm8NRRFmAaU=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=fezPtEiBnDhjbDz4wN3U5wdgfwc0Q4bGyuXYey2P8TrFz5AqvPY/ArPIMlzFIItUFxFslHyO5DJR9l08w7J262vJrn5LkdAOtwEOe1JxiVwgZDuhwp4mD7GzetuXn1xBvOoVrAUnd3zh2qNj8bwpkgkMGHkius7kUCKdpvVK9Oo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=2cq1LWtj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="2cq1LWtj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3FBD6C4CECF; Tue, 5 Nov 2024 16:36:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730824565; bh=FRUBLc9XwIwvwKoViBevKsXG4ZuvaTF1gm8NRRFmAaU=; h=Subject:To:Cc:From:Date:From; b=2cq1LWtjLSIeu4VpK62Pbl/jpyUQxE4wt6uLtgsX6VMNVTausIaBmFb43KfqoRlkB zyaed/qenwlSbuD8pQALCia71RmUysBS1fGnjRrFDHVtkR6oZ+WOsOS3W6NAgpqIb0 tR9XysrhhRO/fJgt1OR9v2aZ4hozWd6sBPeGMIa0= Subject: FAILED: patch "[PATCH] mm: shmem: fix data-race in shmem_getattr()" failed to apply to 6.1-stable tree To: aha310510@gmail.com,akpm@linux-foundation.org,hughd@google.com,stable@vger.kernel.org,syzkaller@googlegroup.com,yuzhao@google.com Cc: From: Date: Tue, 05 Nov 2024 17:35:47 +0100 Message-ID: <2024110547-snooper-saint-e58c@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-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 . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x d949d1d14fa281ace388b1de978e8f2cd52875cf # git commit -s git send-email --to '' --in-reply-to '2024110547-snooper-saint-e58c@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ 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 diff --git a/mm/shmem.c b/mm/shmem.c index c5adb987b23c..4ba1d00fabda 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;