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fanotify: WARN_ON against too large file handles

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struct fanotify_error_event, at least, is preallocated and isn't able to
to handle arbitrarily large file handles.  Future-proof the code by
complaining loudly if a handle larger than MAX_HANDLE_SZ is ever found.

Link: https://lore.kernel.org/r/20211025192746.66445-26-krisman@collabora.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Gabriel Krisman Bertazi 2021-10-25 16:27:40 -03:00 committed by Jan Kara
parent 4bd5a5c8e6
commit 572c28f27a
1 changed files with 11 additions and 1 deletions
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12
fs/notify/fanotify/fanotify.c
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@ -360,13 +360,23 @@ static u32 fanotify_group_event_mask(struct fsnotify_group *group,
static int fanotify_encode_fh_len(struct inode *inode)
{
int dwords = 0;
int fh_len;
if (!inode)
return 0;
exportfs_encode_inode_fh(inode, NULL, &dwords, NULL);
fh_len = dwords << 2;
return dwords << 2;
/*
* struct fanotify_error_event might be preallocated and is
* limited to MAX_HANDLE_SZ. This should never happen, but
* safeguard by forcing an invalid file handle.
*/
if (WARN_ON_ONCE(fh_len > MAX_HANDLE_SZ))
return 0;
return fh_len;
}
/*