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Message-ID: <Z4VflI183-oKSU-h@google.com>
Date: Mon, 13 Jan 2025 18:46:44 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
syzbot+69f5379a1717a0b982a1@...kaller.appspotmail.com
Subject: Re: [PATCH] f2fs: fix to do sanity check correctly on
i_inline_xattr_size
On 01/10, Chao Yu wrote:
> On 1/8/25 03:28, Jaegeuk Kim wrote:
> > On 12/16, Chao Yu wrote:
> > > syzbot reported an out-of-range access issue as below:
> > >
> > > UBSAN: array-index-out-of-bounds in fs/f2fs/f2fs.h:3292:19
> > > index 18446744073709550491 is out of range for type '__le32[923]' (aka 'unsigned int[923]')
> > > CPU: 0 UID: 0 PID: 5338 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-10689-g7af08b57bcb9 #0
> > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> > > Call Trace:
> > > <TASK>
> > > __dump_stack lib/dump_stack.c:94 [inline]
> > > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
> > > ubsan_epilogue lib/ubsan.c:231 [inline]
> > > __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:429
> > > read_inline_xattr+0x273/0x280
> > > lookup_all_xattrs fs/f2fs/xattr.c:341 [inline]
> > > f2fs_getxattr+0x57b/0x13b0 fs/f2fs/xattr.c:533
> > > vfs_getxattr_alloc+0x472/0x5c0 fs/xattr.c:393
> > > ima_read_xattr+0x38/0x60 security/integrity/ima/ima_appraise.c:229
> > > process_measurement+0x117a/0x1fb0 security/integrity/ima/ima_main.c:353
> > > ima_file_check+0xd9/0x120 security/integrity/ima/ima_main.c:572
> > > security_file_post_open+0xb9/0x280 security/security.c:3121
> > > do_open fs/namei.c:3830 [inline]
> > > path_openat+0x2ccd/0x3590 fs/namei.c:3987
> > > do_file_open_root+0x3a7/0x720 fs/namei.c:4039
> > > file_open_root+0x247/0x2a0 fs/open.c:1382
> > > do_handle_open+0x85b/0x9d0 fs/fhandle.c:414
> > > do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> > > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> > > entry_SYSCALL_64_after_hwframe+0x77/0x7f
> > >
> > > index: 18446744073709550491 (decimal, unsigned long long)
> > > = 0xfffffffffffffb9b (hexadecimal) = -1125 (decimal, long long)
> > > UBSAN detects that inline_xattr_addr() tries to access .i_addr[-1125].
> > >
> > > w/ below testcase, it can reproduce this bug easily:
> > > - mkfs.f2fs -f -O extra_attr,flexible_inline_xattr /dev/sdb
> > > - mount -o inline_xattr_size=512 /dev/sdb /mnt/f2fs
> > > - touch /mnt/f2fs/file
> > > - umount /mnt/f2fs
> > > - inject.f2fs --node --mb i_inline --nid 4 --val 0x1 /dev/sdb
> > > - inject.f2fs --node --mb i_inline_xattr_size --nid 4 --val 2048 /dev/sdb
> > > - mount /dev/sdb /mnt/f2fs
> > > - getfattr /mnt/f2fs/file
> > >
> > > The root cause is if metadata of filesystem and inode were fuzzed as below:
> > > - extra_attr feature is enabled
> > > - flexible_inline_xattr feature is enabled
> > > - ri.i_inline_xattr_size = 2048
> > > - F2FS_EXTRA_ATTR bit in ri.i_inline was not set
> > >
> > > sanity_check_inode() will skip doing sanity check on fi->i_inline_xattr_size,
> > > result in using invalid inline_xattr_size later incorrectly, fix it.
> > >
> > > Meanwhile, let's fix to check lower boundary for .i_inline_xattr_size w/
> > > MIN_INLINE_XATTR_SIZE like we did in parse_options().
> > >
> > > Fixes: 6afc662e68b5 ("f2fs: support flexible inline xattr size")
> > > Reported-by: syzbot+69f5379a1717a0b982a1@...kaller.appspotmail.com
> > > Closes: https://lore.kernel.org/linux-f2fs-devel/674f4e7d.050a0220.17bd51.004f.GAE@google.com
> > > Signed-off-by: Chao Yu <chao@...nel.org>
> > > ---
> > > fs/f2fs/inode.c | 19 ++++++++++---------
> > > 1 file changed, 10 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> > > index 282fd320bdb3..29ccc64faae9 100644
> > > --- a/fs/f2fs/inode.c
> > > +++ b/fs/f2fs/inode.c
> > > @@ -302,15 +302,6 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page)
> > > F2FS_TOTAL_EXTRA_ATTR_SIZE);
> > > return false;
> > > }
> > > - if (f2fs_sb_has_flexible_inline_xattr(sbi) &&
> > > - f2fs_has_inline_xattr(inode) &&
> > > - (!fi->i_inline_xattr_size ||
> > > - fi->i_inline_xattr_size > MAX_INLINE_XATTR_SIZE)) {
> > > - f2fs_warn(sbi, "%s: inode (ino=%lx) has corrupted i_inline_xattr_size: %d, max: %lu",
> > > - __func__, inode->i_ino, fi->i_inline_xattr_size,
> > > - MAX_INLINE_XATTR_SIZE);
> > > - return false;
> > > - }
> > > if (f2fs_sb_has_compression(sbi) &&
> > > fi->i_flags & F2FS_COMPR_FL &&
> > > F2FS_FITS_IN_INODE(ri, fi->i_extra_isize,
> > > @@ -320,6 +311,16 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page)
> > > }
> > > }
> > > + if (f2fs_sb_has_flexible_inline_xattr(sbi) &&
> > > + f2fs_has_inline_xattr(inode) &&
> > > + (fi->i_inline_xattr_size < MIN_INLINE_XATTR_SIZE ||
> > > + fi->i_inline_xattr_size > MAX_INLINE_XATTR_SIZE)) {
> > > + f2fs_warn(sbi, "%s: inode (ino=%lx) has corrupted i_inline_xattr_size: %d, min: %u, max: %lu",
> > --> %lu?
>
> Thanks for fixing.
>
> I'd like to fix this in v2, meanwhile including more information from Qasdev's
> patch.
Ok, let me know.
>
> Thanks,
>
> > > + __func__, inode->i_ino, fi->i_inline_xattr_size,
> > > + MIN_INLINE_XATTR_SIZE, MAX_INLINE_XATTR_SIZE);
> > > + return false;
> > > + }
> > > +
> > > if (!f2fs_sb_has_extra_attr(sbi)) {
> > > if (f2fs_sb_has_project_quota(sbi)) {
> > > f2fs_warn(sbi, "%s: corrupted inode ino=%lx, wrong feature flag: %u, run fsck to fix.",
> > > --
> > > 2.40.1
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