From: Ye Bin yebin10@huawei.com

[ Upstream commit 5701875f9609b000d91351eaa6bfd97fe2f157f4 ]

There's issue as follows: BUG: KASAN: use-after-free in ext4_xattr_inode_dec_ref_all+0x6ff/0x790 Read of size 4 at addr ffff88807b003000 by task syz-executor.0/15172

CPU: 3 PID: 15172 Comm: syz-executor.0 Call Trace: __dump_stack lib/dump_stack.c:82 [inline] dump_stack+0xbe/0xfd lib/dump_stack.c:123 print_address_description.constprop.0+0x1e/0x280 mm/kasan/report.c:400 __kasan_report.cold+0x6c/0x84 mm/kasan/report.c:560 kasan_report+0x3a/0x50 mm/kasan/report.c:585 ext4_xattr_inode_dec_ref_all+0x6ff/0x790 fs/ext4/xattr.c:1137 ext4_xattr_delete_inode+0x4c7/0xda0 fs/ext4/xattr.c:2896 ext4_evict_inode+0xb3b/0x1670 fs/ext4/inode.c:323 evict+0x39f/0x880 fs/inode.c:622 iput_final fs/inode.c:1746 [inline] iput fs/inode.c:1772 [inline] iput+0x525/0x6c0 fs/inode.c:1758 ext4_orphan_cleanup fs/ext4/super.c:3298 [inline] ext4_fill_super+0x8c57/0xba40 fs/ext4/super.c:5300 mount_bdev+0x355/0x410 fs/super.c:1446 legacy_get_tree+0xfe/0x220 fs/fs_context.c:611 vfs_get_tree+0x8d/0x2f0 fs/super.c:1576 do_new_mount fs/namespace.c:2983 [inline] path_mount+0x119a/0x1ad0 fs/namespace.c:3316 do_mount+0xfc/0x110 fs/namespace.c:3329 __do_sys_mount fs/namespace.c:3540 [inline] __se_sys_mount+0x219/0x2e0 fs/namespace.c:3514 do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x67/0xd1

Memory state around the buggy address: ffff88807b002f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88807b002f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ffff88807b003000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff

^ ffff88807b003080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff88807b003100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff

Above issue happens as ext4_xattr_delete_inode() isn't check xattr is valid if xattr is in inode. To solve above issue call xattr_check_inode() check if xattr if valid in inode. In fact, we can directly verify in ext4_iget_extra_inode(), so that there is no divergent verification.

Fixes: e50e5129f384 ("ext4: xattr-in-inode support") Signed-off-by: Ye Bin yebin10@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://patch.msgid.link/20250208063141.1539283-3-yebin@huaweicloud.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: David Nyström david.nystrom@est.tech --- fs/ext4/inode.c | 5 +++++ fs/ext4/xattr.c | 26 +------------------------- fs/ext4/xattr.h | 7 +++++++ 3 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 97f7cac0d349..719d9a2bc5a7 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4650,6 +4650,11 @@ static inline int ext4_iget_extra_inode(struct inode *inode, *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) { int err;

+ err = xattr_check_inode(inode, IHDR(inode, raw_inode), + ITAIL(inode, raw_inode)); + if (err) + return err; + ext4_set_inode_state(inode, EXT4_STATE_XATTR); err = ext4_find_inline_data_nolock(inode); if (!err && ext4_has_inline_data(inode)) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 73a9b2934865..16b9c87fd3d8 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -263,7 +263,7 @@ __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh, __ext4_xattr_check_block((inode), (bh), __func__, __LINE__)

-static int +int __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, void *end, const char *function, unsigned int line) { @@ -280,9 +280,6 @@ __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, return error; }

-#define xattr_check_inode(inode, header, end) \ - __xattr_check_inode((inode), (header), (end), __func__, __LINE__) - static int xattr_find_entry(struct inode *inode, struct ext4_xattr_entry **pentry, void *end, int name_index, const char *name, int sorted) @@ -600,9 +597,6 @@ ext4_xattr_ibody_get(struct inode *inode, int name_index, const char *name, raw_inode = ext4_raw_inode(&iloc); header = IHDR(inode, raw_inode); end = ITAIL(inode, raw_inode); - error = xattr_check_inode(inode, header, end); - if (error) - goto cleanup; entry = IFIRST(header); error = xattr_find_entry(inode, &entry, end, name_index, name, 0); if (error) @@ -734,7 +728,6 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size) struct ext4_xattr_ibody_header *header; struct ext4_inode *raw_inode; struct ext4_iloc iloc; - void *end; int error;

if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR)) @@ -744,14 +737,9 @@ ext4_xattr_ibody_list(struct dentry *dentry, char *buffer, size_t buffer_size) return error; raw_inode = ext4_raw_inode(&iloc); header = IHDR(inode, raw_inode); - end = ITAIL(inode, raw_inode); - error = xattr_check_inode(inode, header, end); - if (error) - goto cleanup; error = ext4_xattr_list_entries(dentry, IFIRST(header), buffer, buffer_size);

-cleanup: brelse(iloc.bh); return error; } @@ -815,7 +803,6 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage) struct ext4_xattr_ibody_header *header; struct ext4_xattr_entry *entry; qsize_t ea_inode_refs = 0; - void *end; int ret;

lockdep_assert_held_read(&EXT4_I(inode)->xattr_sem); @@ -826,10 +813,6 @@ int ext4_get_inode_usage(struct inode *inode, qsize_t *usage) goto out; raw_inode = ext4_raw_inode(&iloc); header = IHDR(inode, raw_inode); - end = ITAIL(inode, raw_inode); - ret = xattr_check_inode(inode, header, end); - if (ret) - goto out;

for (entry = IFIRST(header); !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) @@ -2217,9 +2200,6 @@ int ext4_xattr_ibody_find(struct inode *inode, struct ext4_xattr_info *i, is->s.here = is->s.first; is->s.end = ITAIL(inode, raw_inode); if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) { - error = xattr_check_inode(inode, header, is->s.end); - if (error) - return error; /* Find the named attribute. */ error = xattr_find_entry(inode, &is->s.here, is->s.end, i->name_index, i->name, 0); @@ -2743,10 +2723,6 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize, min_offs = end - base; total_ino = sizeof(struct ext4_xattr_ibody_header) + sizeof(u32);

- error = xattr_check_inode(inode, header, end); - if (error) - goto cleanup; - ifree = ext4_xattr_free_space(base, &min_offs, base, &total_ino); if (ifree >= isize_diff) goto shift; diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h index 9a596e19c2b1..cbf235422aec 100644 --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -210,6 +210,13 @@ extern int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode, extern struct mb_cache *ext4_xattr_create_cache(void); extern void ext4_xattr_destroy_cache(struct mb_cache *);

+extern int +__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header, + void *end, const char *function, unsigned int line); + +#define xattr_check_inode(inode, header, end) \ + __xattr_check_inode((inode), (header), (end), __func__, __LINE__) + #ifdef CONFIG_EXT4_FS_SECURITY extern int ext4_init_security(handle_t *handle, struct inode *inode, struct inode *dir, const struct qstr *qstr);