diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2025-07-16 21:35:06 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-07-24 08:58:30 +0200 |
| commit | a4f9c7846b1ac428921ce9676b1b8c80ed60093c (patch) | |
| tree | 91ba8c2664eb225771faf05515b22d86c51669b2 /arch/s390/net/bpf_jit_comp.c | |
| parent | 4c93351a8d4372d35ee1c09a7af5c1092deb6f49 (diff) | |
s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL again
commit 6a5abf8cf182f577c7ae6c62f14debc9754ec986 upstream.
Commit 7ded842b356d ("s390/bpf: Fix bpf_plt pointer arithmetic") has
accidentally removed the critical piece of commit c730fce7c70c
("s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL"), causing
intermittent kernel panics in e.g. perf's on_switch() prog to reappear.
Restore the fix and add a comment.
Fixes: 7ded842b356d ("s390/bpf: Fix bpf_plt pointer arithmetic")
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20250716194524.48109-2-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/s390/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/s390/net/bpf_jit_comp.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 945106b5562db..396cde0f48e37 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -544,7 +544,15 @@ static void bpf_jit_plt(struct bpf_plt *plt, void *ret, void *target) { memcpy(plt, &bpf_plt, sizeof(*plt)); plt->ret = ret; - plt->target = target; + /* + * (target == NULL) implies that the branch to this PLT entry was + * patched and became a no-op. However, some CPU could have jumped + * to this PLT entry before patching and may be still executing it. + * + * Since the intention in this case is to make the PLT entry a no-op, + * make the target point to the return label instead of NULL. + */ + plt->target = target ?: ret; } /* |