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From: Chuck Lever <chuck.lever@oracle.com>
To: bfields@fieldses.org
Cc: linux-nfs@vger.kernel.org
Subject: [PATCH RFC 1/2] SUNRPC: Set rcv_buf->len correctly in gss_unwrap_kerberos_v2()
Date: Thu, 23 Jul 2020 19:14:45 -0400	[thread overview]
Message-ID: <159554608522.6546.6837849890434723341.stgit@klimt.1015granger.net> (raw)
In-Reply-To: <159554528704.6546.6823326959131917327.stgit@klimt.1015granger.net>

Braino when converting "buf->len -=" to "buf->len = len -".

The result is under-estimation of the ralign and rslack values. On
krb5p mounts, this has caused READDIR to fail with EIO, and KASAN
splats when decoding READLINK replies.

Reported-by: Marian Rainer-Harbach
Reported-by: Pierre Sauter <pierre.sauter@stwm.de>
BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1886277
Fixes: 31c9590ae468 ("SUNRPC: Add "@len" parameter to gss_unwrap()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/auth_gss/gss_krb5_wrap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index cf0fd170ac18..90b8329fef82 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -584,7 +584,7 @@ gss_unwrap_kerberos_v2(struct krb5_ctx *kctx, int offset, int len,
 							buf->head[0].iov_len);
 	memmove(ptr, ptr + GSS_KRB5_TOK_HDR_LEN + headskip, movelen);
 	buf->head[0].iov_len -= GSS_KRB5_TOK_HDR_LEN + headskip;
-	buf->len = len - GSS_KRB5_TOK_HDR_LEN + headskip;
+	buf->len = len - (GSS_KRB5_TOK_HDR_LEN + headskip);
 
 	/* Trim off the trailing "extra count" and checksum blob */
 	xdr_buf_trim(buf, ec + GSS_KRB5_TOK_HDR_LEN + tailskip);



  reply	other threads:[~2020-07-23 23:14 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-23 23:14 [PATCH RFC 0/2] Fix problems with NFSv4 on krb5p Chuck Lever
2020-07-23 23:14 ` Chuck Lever [this message]
2020-07-23 23:14 ` [PATCH RFC 2/2] SUNRPC: Fix buf->len calculation in unwrap_priv_data() Chuck Lever

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