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efivarfs: use I_MUTEX_CHILD nested lock to traverse variables on resume

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syzbot warns about a potential deadlock, but this is a false positive
resulting from a missing lockdep annotation: iterate_dir() locks the
parent whereas the inode_lock() it warns about locks the child, which is
guaranteed to be a different lock.

So use inode_lock_nested() instead with the appropriate lock class.

Reported-by: syzbot+019072ad24ab1d948228@syzkaller.appspotmail.com
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Ard Biesheuvel 2025-03-17 08:23:11 +01:00
parent cb16dfed00
commit dec1277875
1 changed files with 1 additions and 1 deletions
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2
fs/efivarfs/super.c
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@ -421,7 +421,7 @@ static bool efivarfs_actor(struct dir_context *ctx, const char *name, int len,
if (err)
size = 0;
inode_lock(inode);
inode_lock_nested(inode, I_MUTEX_CHILD);
i_size_write(inode, size);
inode_unlock(inode);