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Message-Id: <20250208063141.1539283-3-yebin@huaweicloud.com>
Date: Sat, 8 Feb 2025 14:31:41 +0800
From: Ye Bin <yebin@...weicloud.com>
To: tytso@....edu,
adilger.kernel@...ger.ca,
linux-ext4@...r.kernel.org
Cc: jack@...e.cz
Subject: [PATCH v2 2/2] ext4: fix out-of-bound read in ext4_xattr_inode_dec_ref_all()
From: Ye Bin <yebin10@...wei.com>
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@...wei.com>
---
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 7c54ae5fcbd4..af735386aa44 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4674,6 +4674,11 @@ 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 0e4494863d15..a10fb8a9d02d 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -308,7 +308,7 @@ __ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh,
__ext4_xattr_check_block((inode), (bh), __func__, __LINE__)
-static inline int
+int
__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
void *end, const char *function, unsigned int line)
{
@@ -316,9 +316,6 @@ __xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,
function, line);
}
-#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)
@@ -650,9 +647,6 @@ 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)
@@ -783,7 +777,6 @@ 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))
@@ -793,14 +786,9 @@ 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;
}
@@ -868,7 +856,6 @@ 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);
@@ -879,10 +866,6 @@ 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))
@@ -2237,9 +2220,6 @@ 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);
@@ -2790,10 +2770,6 @@ 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 5197f17ffd9a..1fedf44d4fb6 100644
--- a/fs/ext4/xattr.h
+++ b/fs/ext4/xattr.h
@@ -209,6 +209,13 @@ 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);
--
2.34.1
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