From 4597554b4f7b29e7fd78aa449bab648f8da4ee2c Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 12 May 2023 15:11:02 -0400
Subject: [PATCH] ext4: add bounds checking in
get_max_inline_xattr_value_size()
commit 2220eaf90992c11d888fe771055d4de330385f01 upstream.
Normally the extended attributes in the inode body would have been
checked when the inode is first opened, but if someone is writing to
the block device while the file system is mounted, it's possible for
the inode table to get corrupted. Add bounds checking to avoid
reading beyond the end of allocated memory if this happens.
Reported-by: syzbot+1966db24521e5f6e23f7@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=1966db24521e5f6e23f7
Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/ext4/inline.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index fd0567d0219ce..d0bd1046f4a0f 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -32,6 +32,7 @@ static int get_max_inline_xattr_value_size(struct inode *inode,
struct ext4_xattr_ibody_header *header;
struct ext4_xattr_entry *entry;
struct ext4_inode *raw_inode;
+ void *end;
int free, min_offs;
if (!EXT4_INODE_HAS_XATTR_SPACE(inode))
@@ -55,14 +56,23 @@ static int get_max_inline_xattr_value_size(struct inode *inode,
raw_inode = ext4_raw_inode(iloc);
header = IHDR(inode, raw_inode);
entry = IFIRST(header);
+ end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
/* Compute min_offs. */
- for (; !IS_LAST_ENTRY(entry); entry = EXT4_XATTR_NEXT(entry)) {
+ while (!IS_LAST_ENTRY(entry)) {
+ void *next = EXT4_XATTR_NEXT(entry);
+
+ if (next >= end) {
+ EXT4_ERROR_INODE(inode,
+ "corrupt xattr in inline inode");
+ return 0;
+ }
if (!entry->e_value_inum && entry->e_value_size) {
size_t offs = le16_to_cpu(entry->e_value_offs);
if (offs < min_offs)
min_offs = offs;
}
+ entry = next;
}
free = min_offs -
((void *)entry - (void *)IFIRST(header)) - sizeof(__u32);
--
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