linux-kernel - [PATCH AUTOSEL 5.4 3/5] bpf: use kvzmalloc to allocate BPF verifier environment

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Message-ID: <20241023143310.2982725-3-sashal@kernel.org>
Date: Wed, 23 Oct 2024 10:33:06 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Rik van Riel <riel@...riel.com>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Alexei Starovoitov <ast@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	daniel@...earbox.net,
	andrii@...nel.org,
	bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 3/5] bpf: use kvzmalloc to allocate BPF verifier environment

From: Rik van Riel <riel@...riel.com>

[ Upstream commit 434247637c66e1be2bc71a9987d4c3f0d8672387 ]

The kzmalloc call in bpf_check can fail when memory is very fragmented,
which in turn can lead to an OOM kill.

Use kvzmalloc to fall back to vmalloc when memory is too fragmented to
allocate an order 3 sized bpf verifier environment.

Admittedly this is not a very common case, and only happens on systems
where memory has already been squeezed close to the limit, but this does
not seem like much of a hot path, and it's a simple enough fix.

Signed-off-by: Rik van Riel <riel@...riel.com>
Reviewed-by: Shakeel Butt <shakeel.butt@...ux.dev>
Link: https://lore.kernel.org/r/20241008170735.16766766@imladris.surriel.com
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/bpf/verifier.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0901911b42b56..013b9062c47c3 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -9558,7 +9558,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 	/* 'struct bpf_verifier_env' can be global, but since it's not small,
 	 * allocate/free it every time bpf_check() is called
 	 */
-	env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
+	env = kvzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
 	if (!env)
 		return -ENOMEM;
 	log = &env->log;
@@ -9728,6 +9728,6 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
 		mutex_unlock(&bpf_verifier_lock);
 	vfree(env->insn_aux_data);
 err_free_env:
-	kfree(env);
+	kvfree(env);
 	return ret;
 }
-- 
2.43.0