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NFSD: fix nfsd4_listxattr_validate_cookie

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If LISTXATTRS is sent with a correct cookie but a small maxcount,
this could lead function nfsd4_listxattr_validate_cookie to
return NFS4ERR_BAD_COOKIE. If maxcount = 20, then second check
on function gives RHS = 3 thus any cookie larger than 3 returns
NFS4ERR_BAD_COOKIE.

There is no need to validate the cookie on the return XDR buffer
since attribute referenced by cookie will be the first in the
return buffer.

Fixes: 23e50fe3a5e6 ("nfsd: implement the xattr functions and en/decode logic")
Signed-off-by: Jorge Mora <mora@netapp.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jorge Mora 2024-01-25 07:46:54 -07:00 committed by Chuck Lever
parent 5ff318f645
commit 52a357db80
1 changed files with 1 additions and 6 deletions
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7
fs/nfsd/nfs4xdr.c
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@ -5386,16 +5386,11 @@ nfsd4_listxattr_validate_cookie(struct nfsd4_listxattrs *listxattrs,
/*
* If the cookie is larger than the maximum number we can fit
* in either the buffer we just got back from vfs_listxattr, or,
* XDR-encoded, in the return buffer, it's invalid.
* in the buffer we just got back from vfs_listxattr, it's invalid.
*/
if (cookie > (listxattrs->lsxa_len) / (XATTR_USER_PREFIX_LEN + 2))
return nfserr_badcookie;
if (cookie > (listxattrs->lsxa_maxcount /
(XDR_QUADLEN(XATTR_USER_PREFIX_LEN + 2) + 4)))
return nfserr_badcookie;
*offsetp = (u32)cookie;
return 0;
}