This is a note to let you know that I've just added the patch titled
bpf: Add explicit cast to 'void *' for __BPF_DISPATCHER_UPDATE()
to the 6.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-add-explicit-cast-to-void-for-__bpf_dispatcher_update.patch
and it can be found in the queue-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a679120edfcf3d63f066f53afd425d51b480e533 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <nathan@xxxxxxxxxx>
Date: Mon, 7 Nov 2022 10:07:11 -0700
Subject: bpf: Add explicit cast to 'void *' for __BPF_DISPATCHER_UPDATE()
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From: Nathan Chancellor <nathan@xxxxxxxxxx>
commit a679120edfcf3d63f066f53afd425d51b480e533 upstream.
When building with clang:
kernel/bpf/dispatcher.c:126:33: error: pointer type mismatch ('void *' and 'unsigned int (*)(const void *, const struct bpf_insn *, bpf_func_t)' (aka 'unsigned int (*)(const void *, const struct bpf_insn *, unsigned int (*)(const void *, const struct bpf_insn *))')) [-Werror,-Wpointer-type-mismatch]
__BPF_DISPATCHER_UPDATE(d, new ?: &bpf_dispatcher_nop_func);
~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/bpf.h:1045:54: note: expanded from macro '__BPF_DISPATCHER_UPDATE'
__static_call_update((_d)->sc_key, (_d)->sc_tramp, (_new))
^~~~
1 error generated.
The warning is pointing out that the type of new ('void *') and
&bpf_dispatcher_nop_func are not compatible, which could have side
effects coming out of a conditional operator due to promotion rules.
Add the explicit cast to 'void *' to make it clear that this is
expected, as __BPF_DISPATCHER_UPDATE() expands to a call to
__static_call_update(), which expects a 'void *' as its final argument.
Fixes: c86df29d11df ("bpf: Convert BPF_DISPATCHER to use static_call() (not ftrace)")
Link: https://github.com/ClangBuiltLinux/linux/issues/1755
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Acked-by: Björn Töpel <bjorn@xxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Link: https://lore.kernel.org/r/20221107170711.42409-1-nathan@xxxxxxxxxx
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/bpf/dispatcher.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/bpf/dispatcher.c
+++ b/kernel/bpf/dispatcher.c
@@ -123,7 +123,7 @@ static void bpf_dispatcher_update(struct
return;
}
- __BPF_DISPATCHER_UPDATE(d, new ?: &bpf_dispatcher_nop_func);
+ __BPF_DISPATCHER_UPDATE(d, new ?: (void *)&bpf_dispatcher_nop_func);
if (new)
d->image_off = noff;
Patches currently in stable-queue which might be from nathan@xxxxxxxxxx are
queue-6.0/gcov-clang-fix-the-buffer-overflow-issue.patch
queue-6.0/risc-v-vdso-do-not-add-missing-symbols-to-version-se.patch
queue-6.0/bpf-add-explicit-cast-to-void-for-__bpf_dispatcher_update.patch
queue-6.0/s390-always-build-relocatable-kernel.patch
