linux-kernel - [PATCH] NFS: check for allocation failure from mempool

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Message-Id: <20200226234320.7722-1-colin.king@canonical.com>
Date:   Wed, 26 Feb 2020 23:43:20 +0000
From:   Colin King <colin.king@...onical.com>
To:     Trond Myklebust <trond.myklebust@...merspace.com>,
        Anna Schumaker <anna.schumaker@...app.com>,
        linux-nfs@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] NFS: check for allocation failure from mempool_alloc

From: Colin Ian King <colin.king@...onical.com>

It is possible for mempool_alloc to return null when using
the GFP_KERNEL flag, so return NULL and avoid a null pointer
dereference on the following memset of the null pointer.

Addresses-Coverity: ("Dereference null return")
Fixes: 2b17d725f9be ("NFS: Clean up writeback code")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 fs/nfs/write.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index c478b772cc49..7ca036660dd1 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -106,6 +106,9 @@ static struct nfs_pgio_header *nfs_writehdr_alloc(void)
 {
 	struct nfs_pgio_header *p = mempool_alloc(nfs_wdata_mempool, GFP_KERNEL);
 
+	if (!p)
+		return NULL;
+
 	memset(p, 0, sizeof(*p));
 	p->rw_mode = FMODE_WRITE;
 	return p;
-- 
2.25.0