linux-kernel - [PATCH AUTOSEL 6.7 083/108] x86/cfi,bpf: Fix bpf_exception

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Date: Tue, 16 Jan 2024 14:39:49 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	daniel@...earbox.net,
	andrii@...nel.org,
	bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 6.7 083/108] x86/cfi,bpf: Fix bpf_exception_cb() signature

From: Alexei Starovoitov <alexei.starovoitov@...il.com>

[ Upstream commit 852486b35f344887786d63250946dd921a05d7e8 ]

As per the earlier patches, BPF sub-programs have bpf_callback_t
signature and CFI expects callers to have matching signature. This is
violated by bpf_prog_aux::bpf_exception_cb().

[peterz: Changelog]
Reported-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@...il.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/CAADnVQ+Z7UcXXBBhMubhcMM=R-dExk-uHtfOLtoLxQ1XxEpqEA@mail.gmail.com
Link: https://lore.kernel.org/r/20231215092707.910319166@infradead.org
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/bpf.h  | 2 +-
 kernel/bpf/helpers.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 741af9e5cb9d..8ebaaab5fdb5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1442,7 +1442,7 @@ struct bpf_prog_aux {
 	int cgroup_atype; /* enum cgroup_bpf_attach_type */
 	struct bpf_map *cgroup_storage[MAX_BPF_CGROUP_STORAGE_TYPE];
 	char name[BPF_OBJ_NAME_LEN];
-	unsigned int (*bpf_exception_cb)(u64 cookie, u64 sp, u64 bp);
+	u64 (*bpf_exception_cb)(u64 cookie, u64 sp, u64 bp, u64, u64);
 #ifdef CONFIG_SECURITY
 	void *security;
 #endif
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index f43038931935..666e452230ed 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2509,7 +2509,7 @@ __bpf_kfunc void bpf_throw(u64 cookie)
 	 * which skips compiler generated instrumentation to do the same.
 	 */
 	kasan_unpoison_task_stack_below((void *)(long)ctx.sp);
-	ctx.aux->bpf_exception_cb(cookie, ctx.sp, ctx.bp);
+	ctx.aux->bpf_exception_cb(cookie, ctx.sp, ctx.bp, 0, 0);
 	WARN(1, "A call to BPF exception callback should never return\n");
 }
 
-- 
2.43.0