Patch "pipe: Fix buffer offset after partially failed read" has been added to the 3.14-stable tree

This is a note to let you know that I've just added the patch titled

pipe: Fix buffer offset after partially failed read

to the 3.14-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:
pipe-fix-buffer-offset-after-partially-failed-read.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ben Hutchings <[email protected]>
Date: Sat, 13 Feb 2016 02:34:52 +0000
Subject: pipe: Fix buffer offset after partially failed read

From: Ben Hutchings <[email protected]>

commit feae3ca2e5e1a8f44aa6290255d3d9709985d0b2 upstream.

Quoting the RHEL advisory:

The same flawed fix was applied to stable branches from 2.6.32.y to 3.14.y inclusive, and I was able to reproduce the issue on 3.2.y. We need to give pipe_iov_copy_to_user() a separate offset variable and only update the buffer offset if it succeeds.

References: https://rhn.redhat.com/errata/RHSA-2016-0103.html

---
 fs/pipe.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -401,6 +401,7 @@ pipe_read(struct kiocb *iocb, const stru
 			void *addr;
 			size_t chars = buf->len, remaining;
 			int error, atomic;
+			int offset;
 
 			if (chars > total_len)
 				chars = total_len;

@@ -414,9 +415,10 @@ pipe_read(struct kiocb *iocb, const stru
 
 			atomic = !iov_fault_in_pages_write(iov, chars);
 			remaining = chars;
+			offset = buf->offset;
 redo:
 			addr = ops->map(pipe, buf, atomic);
-			error = pipe_iov_copy_to_user(iov, addr, &buf->offset,
+			error = pipe_iov_copy_to_user(iov, addr, &offset,
 						      &remaining, atomic);
 			ops->unmap(pipe, buf, addr);
 			if (unlikely(error)) {

@@ -432,6 +434,7 @@ redo:
 				break;
 			}
 			ret += chars;
+			buf->offset += chars;
 			buf->len -= chars;
 
 			/* Was it a packet buffer? Clean up and exit */

Patches currently in stable-queue which might be from [email protected] are

queue-3.14/pipe-fix-buffer-offset-after-partially-failed-read.patch