linux-kernel - [PATCH 3.16 19/63] jfs: Fix inconsistency between memory allocation and ea_buf->max

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Message-ID: <lsq.1537575342.305835109@decadent.org.uk>
Date:   Sat, 22 Sep 2018 01:15:42 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Dave Kleikamp" <dave.kleikamp@...cle.com>,
        "Shankara Pailoor" <shankarapailoor@...il.com>
Subject: [PATCH 3.16 19/63] jfs: Fix inconsistency between memory
 allocation and ea_buf->max_size

3.16.58-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Shankara Pailoor <shankarapailoor@...il.com>

commit 92d34134193e5b129dc24f8d79cb9196626e8d7a upstream.

The code is assuming the buffer is max_size length, but we weren't
allocating enough space for it.

Signed-off-by: Shankara Pailoor <shankarapailoor@...il.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@...cle.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/jfs/xattr.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

--- a/fs/jfs/xattr.c
+++ b/fs/jfs/xattr.c
@@ -493,15 +493,17 @@ static int ea_get(struct inode *inode, s
 	if (size > PSIZE) {
 		/*
 		 * To keep the rest of the code simple.  Allocate a
-		 * contiguous buffer to work with
+		 * contiguous buffer to work with. Make the buffer large
+		 * enough to make use of the whole extent.
 		 */
-		ea_buf->xattr = kmalloc(size, GFP_KERNEL);
+		ea_buf->max_size = (size + sb->s_blocksize - 1) &
+		    ~(sb->s_blocksize - 1);
+
+		ea_buf->xattr = kmalloc(ea_buf->max_size, GFP_KERNEL);
 		if (ea_buf->xattr == NULL)
 			return -ENOMEM;
 
 		ea_buf->flag = EA_MALLOC;
-		ea_buf->max_size = (size + sb->s_blocksize - 1) &
-		    ~(sb->s_blocksize - 1);
 
 		if (ea_size == 0)
 			return 0;