[PATCH bpf-next v2 2/3] bpf: Fix bpf_throw warning on 32-bit arch

Kumar Kartikeya Dwivedi
2023-09-18T15:57:35Z

On 32-bit architectures, the pointer width is 32-bit, while we try to
cast from a u64 down to it, the compiler complains on mismatch in
integer size. Fix this by first casting to long which should match
the pointer width on targets supported by Linux.

Fixes: ec5290a178b7 ("bpf: Prevent KASAN false positive with bpf_throw")
Reported-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
kernel/bpf/helpers.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 7ff2a42f1996..dd1c69ee3375 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -2488,7 +2488,7 @@ __bpf_kfunc void bpf_throw(u64 cookie)
* deeper stack depths than ctx.sp as we do not return from bpf_throw,
* which skips compiler generated instrumentation to do the same.
*/
- kasan_unpoison_task_stack_below((void *)ctx.sp);
+ kasan_unpoison_task_stack_below((void *)(long)ctx.sp);
ctx.aux->bpf_exception_cb(cookie, ctx.sp, ctx.bp);
WARN(1, "A call to BPF exception callback should never return\n");
}
--
2.41.0