linux-kernel - [PATCH 4.20 197/352] livepatch: check kzalloc return values

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Date:   Mon, 11 Feb 2019 15:17:04 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nicholas Mc Guire <hofrat@...dl.org>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Petr Mladek <pmladek@...e.com>,
        Miroslav Benes <mbenes@...e.cz>, Jiri Kosina <jkosina@...e.cz>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.20 197/352] livepatch: check kzalloc return values

4.20-stable review patch.  If anyone has any objections, please let me know.

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

[ Upstream commit 5f30b2e823484ce6a79f2b59901b6351c15effa6 ]

kzalloc() return should always be checked - notably in example code
where this may be seen as reference. On failure of allocation in
livepatch_fix1_dummy_alloc() respectively dummy_alloc() previous
allocation is freed (thanks to Petr Mladek <pmladek@...e.com> for
catching this) and NULL returned.

Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
Fixes: 439e7271dc2b ("livepatch: introduce shadow variable API")
Acked-by: Joe Lawrence <joe.lawrence@...hat.com>
Reviewed-by: Petr Mladek <pmladek@...e.com>
Acked-by: Miroslav Benes <mbenes@...e.cz>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 samples/livepatch/livepatch-shadow-fix1.c | 5 +++++
 samples/livepatch/livepatch-shadow-mod.c  | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
index 49b13553eaae..e8f1bd6b29b1 100644
--- a/samples/livepatch/livepatch-shadow-fix1.c
+++ b/samples/livepatch/livepatch-shadow-fix1.c
@@ -89,6 +89,11 @@ struct dummy *livepatch_fix1_dummy_alloc(void)
 	 * pointer to handle resource release.
 	 */
 	leak = kzalloc(sizeof(int), GFP_KERNEL);
+	if (!leak) {
+		kfree(d);
+		return NULL;
+	}
+
 	klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
 			 shadow_leak_ctor, leak);
 
diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c
index 4c54b250332d..4aa8a88d3cd6 100644
--- a/samples/livepatch/livepatch-shadow-mod.c
+++ b/samples/livepatch/livepatch-shadow-mod.c
@@ -118,6 +118,10 @@ noinline struct dummy *dummy_alloc(void)
 
 	/* Oops, forgot to save leak! */
 	leak = kzalloc(sizeof(int), GFP_KERNEL);
+	if (!leak) {
+		kfree(d);
+		return NULL;
+	}
 
 	pr_info("%s: dummy @ %p, expires @ %lx\n",
 		__func__, d, d->jiffies_expire);
-- 
2.19.1