From c5fa4eedddd1c8342ce533cb401c0e693e55b4e3 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sun, 30 Apr 2023 03:04:13 -0400 Subject: [PATCH] ext4: fix invalid free tracking in ext4_xattr_move_to_block() commit b87c7cdf2bed4928b899e1ce91ef0d147017ba45 upstream. In ext4_xattr_move_to_block(), the value of the extended attribute which we need to move to an external block may be allocated by kvmalloc() if the value is stored in an external inode. So at the end of the function the code tried to check if this was the case by testing entry->e_value_inum. However, at this point, the pointer to the xattr entry is no longer valid, because it was removed from the original location where it had been stored. So we could end up calling kvfree() on a pointer which was not allocated by kvmalloc(); or we could also potentially leak memory by not freeing the buffer when it should be freed. Fix this by storing whether it should be freed in a separate variable. Cc: stable@kernel.org Link: https://lore.kernel.org/r/20230430160426.581366-1-tytso@mit.edu Link: https://syzkaller.appspot.com/bug?id=5c2aee8256e30b55ccf57312c16d88417adbd5e1 Link: https://syzkaller.appspot.com/bug?id=41a6b5d4917c0412eb3b3c3c604965bed7d7420b Reported-by: syzbot+64b645917ce07d89bde5@syzkaller.appspotmail.com Reported-by: syzbot+0d042627c4f2ad332195@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/xattr.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index b17c1b90e122..b1b8fe86ccdb 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -2564,6 +2564,7 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode, .in_inode = !!entry->e_value_inum, }; struct ext4_xattr_ibody_header *header = IHDR(inode, raw_inode); + int needs_kvfree = 0; int error; is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS); @@ -2586,7 +2587,7 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode, error = -ENOMEM; goto out; } - + needs_kvfree = 1; error = ext4_xattr_inode_get(inode, entry, buffer, value_size); if (error) goto out; @@ -2625,7 +2626,7 @@ static int ext4_xattr_move_to_block(handle_t *handle, struct inode *inode, out: kfree(b_entry_name); - if (entry->e_value_inum && buffer) + if (needs_kvfree && buffer) kvfree(buffer); if (is) brelse(is->iloc.bh);