Commit eb5f5175 authored Apr 13, 2022 by Harshit Mogalapalli Committed by Greg Kroah-Hartman Apr 20, 2022

cifs: potential buffer overflow in handling symlinks



[ Upstream commit 64c4a37ac04eeb43c42d272f6e6c8c12bfcf4304 ]

Smatch printed a warning:
	arch/x86/crypto/poly1305_glue.c:198 poly1305_update_arch() error:
	__memcpy() 'dctx->buf' too small (16 vs u32max)

It's caused because Smatch marks 'link_len' as untrusted since it comes
from sscanf(). Add a check to ensure that 'link_len' is not larger than
the size of the 'link_str' buffer.

Fixes: c69c1b6e ("cifs: implement CIFSParseMFSymlink()")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 1a1748d0

fs/cifs/link.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -97,6 +97,9 @@ parse_mf_symlink(const u8 buf, unsigned int buf_len, unsigned int _link_len,
		if (rc != 1)
		return -EINVAL;

		if (link_len > CIFS_MF_SYMLINK_LINK_MAXLEN)
		return -EINVAL;

		rc = symlink_hash(link_len, link_str, md5_hash);
		if (rc) {
		cifs_dbg(FYI, "%s: MD5 hash failure: %d\n", __func__, rc);