linux-kernel - [PATCH 5.16 0279/1039] libbpf: Fix gen_loader assumption on number of programs.

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Date:   Mon, 24 Jan 2022 19:34:28 +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, Alexei Starovoitov <ast@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0279/1039] libbpf: Fix gen_loader assumption on number of programs.

From: Alexei Starovoitov <ast@...nel.org>

[ Upstream commit 259172bb6514758ce3be1610c500b51a9f44212a ]

libbpf's obj->nr_programs includes static and global functions. That number
could be higher than the actual number of bpf programs going be loaded by
gen_loader. Passing larger nr_programs to bpf_gen__init() doesn't hurt. Those
exra stack slots will stay as zero. bpf_gen__finish() needs to check that
actual number of progs that gen_loader saw is less than or equal to
obj->nr_programs.

Fixes: ba05fd36b851 ("libbpf: Perform map fd cleanup for gen_loader in case of error")
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/lib/bpf/gen_loader.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c
index 4ac65afc99e50..737e7cbe3e547 100644
--- a/tools/lib/bpf/gen_loader.c
+++ b/tools/lib/bpf/gen_loader.c
@@ -371,8 +371,9 @@ int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps)
 {
 	int i;
 
-	if (nr_progs != gen->nr_progs || nr_maps != gen->nr_maps) {
-		pr_warn("progs/maps mismatch\n");
+	if (nr_progs < gen->nr_progs || nr_maps != gen->nr_maps) {
+		pr_warn("nr_progs %d/%d nr_maps %d/%d mismatch\n",
+			nr_progs, gen->nr_progs, nr_maps, gen->nr_maps);
 		gen->error = -EFAULT;
 		return gen->error;
 	}
-- 
2.34.1