bpf: use kvzmalloc to allocate BPF verifier environment

[ 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@surriel.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/r/20241008170735.16766766@imladris.surriel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bb54f1f4fafba57ded18ff5b5fc97335739bc6b6..da90f565317d4c7687c5befffec46781ea109a04 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -15500,7 +15500,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr)
        /* '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;
@@ -15721,6 +15721,6 @@ err_unlock:
                mutex_unlock(&bpf_verifier_lock);
        vfree(env->insn_aux_data);
 err_free_env:
-       kfree(env);
+       kvfree(env);
        return ret;
 }