6.6-stable review patch. If anyone has any objections, please let me know.
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From: Joshua Rogers linux@joshua.hu
commit d4b69a6186b215d2dc1ebcab965ed88e8d41768d upstream.
A zero length gss_token results in pages == 0 and in_token->pages[0] is NULL. The code unconditionally evaluates page_address(in_token->pages[0]) for the initial memcpy, which can dereference NULL even when the copy length is 0. Guard the first memcpy so it only runs when length > 0.
Fixes: 5866efa8cbfb ("SUNRPC: Fix svcauth_gss_proxy_init()") Cc: stable@vger.kernel.org Signed-off-by: Joshua Rogers linux@joshua.hu Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sunrpc/auth_gss/svcauth_gss.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1093,7 +1093,8 @@ static int gss_read_proxy_verf(struct sv }
length = min_t(unsigned int, inlen, (char *)xdr->end - (char *)xdr->p); - memcpy(page_address(in_token->pages[0]), xdr->p, length); + if (length) + memcpy(page_address(in_token->pages[0]), xdr->p, length); inlen -= length;
to_offs = length;