[v3,7/7] x86/cfi,bpf: Fix bpf_exception_cb() signature

Commit Message

Peter Zijlstra Dec. 15, 2023, 9:12 a.m. UTC

From: Alexei Starovoitov <[e-mail]>

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 <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Link: https://lkml.kernel.org/r/CAADnVQ+Z7UcXXBBhMubhcMM=[e-mail]
---
 include/linux/bpf.h  |    2 +-
 kernel/bpf/helpers.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

Patch

--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1484,7 +1484,7 @@  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
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2537,7 +2537,7 @@  __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");
 }