This is a note to let you know that I've just added the patch titled SUNRPC: fix copying of multiple pages in gss_read_proxy_verf() to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sunrpc-fix-copying-of-multiple-pages-in-gss_read_pro.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 633b7c0ec3e2f042a0606b13cb10bbebcca0c7cf Author: Martijn de Gouw <martijn.de.gouw@xxxxxxxxxxxxxxxxxxxxxxxxx> Date: Mon Oct 19 13:42:27 2020 +0200 SUNRPC: fix copying of multiple pages in gss_read_proxy_verf() [ Upstream commit d48c8124749c9a5081fe68680f83605e272c984b ] When the passed token is longer than 4032 bytes, the remaining part of the token must be copied from the rqstp->rq_arg.pages. But the copy must make sure it happens in a consecutive way. With the existing code, the first memcpy copies 'length' bytes from argv->iobase, but since the header is in front, this never fills the whole first page of in_token->pages. The mecpy in the loop copies the following bytes, but starts writing at the next page of in_token->pages. This leaves the last bytes of page 0 unwritten. Symptoms were that users with many groups were not able to access NFS exports, when using Active Directory as the KDC. Signed-off-by: Martijn de Gouw <martijn.de.gouw@xxxxxxxxxxxxxxxxxxxxxxxxx> Fixes: 5866efa8cbfb "SUNRPC: Fix svcauth_gss_proxy_init()" Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c index c28051f7d217d..653c317694406 100644 --- a/net/sunrpc/auth_gss/svcauth_gss.c +++ b/net/sunrpc/auth_gss/svcauth_gss.c @@ -1104,9 +1104,9 @@ static int gss_read_proxy_verf(struct svc_rqst *rqstp, struct gssp_in_token *in_token) { struct kvec *argv = &rqstp->rq_arg.head[0]; - unsigned int page_base, length; - int pages, i, res; - size_t inlen; + unsigned int length, pgto_offs, pgfrom_offs; + int pages, i, res, pgto, pgfrom; + size_t inlen, to_offs, from_offs; res = gss_read_common_verf(gc, argv, authp, in_handle); if (res) @@ -1134,17 +1134,24 @@ static int gss_read_proxy_verf(struct svc_rqst *rqstp, memcpy(page_address(in_token->pages[0]), argv->iov_base, length); inlen -= length; - i = 1; - page_base = rqstp->rq_arg.page_base; + to_offs = length; + from_offs = rqstp->rq_arg.page_base; while (inlen) { - length = min_t(unsigned int, inlen, PAGE_SIZE); - memcpy(page_address(in_token->pages[i]), - page_address(rqstp->rq_arg.pages[i]) + page_base, + pgto = to_offs >> PAGE_SHIFT; + pgfrom = from_offs >> PAGE_SHIFT; + pgto_offs = to_offs & ~PAGE_MASK; + pgfrom_offs = from_offs & ~PAGE_MASK; + + length = min_t(unsigned int, inlen, + min_t(unsigned int, PAGE_SIZE - pgto_offs, + PAGE_SIZE - pgfrom_offs)); + memcpy(page_address(in_token->pages[pgto]) + pgto_offs, + page_address(rqstp->rq_arg.pages[pgfrom]) + pgfrom_offs, length); + to_offs += length; + from_offs += length; inlen -= length; - page_base = 0; - i++; } return 0; }