[PATCH bpf-next] bpf, x86_64: fail gracefully on bpf_jit_binary_pack_finalize failures

Instead of BUG_ON(), fail gracefully and return orig_prog.

Fixes: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Signed-off-by: Song Liu <song@kernel.org>
---
 arch/x86/net/bpf_jit_comp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 643f38b91e30..08e8fd8f954a 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c

@@ -2380,7 +2380,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 			 *
 			 * Both cases are serious bugs that we should not continue.
 			 */
-			BUG_ON(bpf_jit_binary_pack_finalize(prog, header, rw_header));
+			if (WARN_ON(bpf_jit_binary_pack_finalize(prog, header, rw_header))) {
+				prog = orig_prog;
+				goto out_addrs;
+			}
+
 			bpf_tail_call_direct_fixup(prog);
 		} else {
 			jit_data->addrs = addrs;

-- 
2.30.2

On Mon, Feb 7, 2022 at 10:26 PM Song Liu [off-list ref] wrote:

I tweaked that comment a bit, since it's no longer accurate and
pushed to bpf-next.
Thanks!

                         */
-                       BUG_ON(bpf_jit_binary_pack_finalize(prog, header, rw_header));
+                       if (WARN_ON(bpf_jit_binary_pack_finalize(prog, header, rw_header))) {
+                               prog = orig_prog;
+                               goto out_addrs;
+                       }
+
                        bpf_tail_call_direct_fixup(prog);
                } else {
                        jit_data->addrs = addrs;
--
2.30.2

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov [off-list ref]:

On Mon, 7 Feb 2022 22:25:33 -0800 you wrote:

Instead of BUG_ON(), fail gracefully and return orig_prog.

Fixes: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Signed-off-by: Song Liu <song@kernel.org>
---
 arch/x86/net/bpf_jit_comp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

Here is the summary with links:
  - [bpf-next] bpf, x86_64: fail gracefully on bpf_jit_binary_pack_finalize failures
    https://git.kernel.org/bpf/bpf-next/c/f95f768f0af4

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

On Feb 8, 2022, at 9:28 AM, Alexei Starovoitov [off-list ref] wrote:

On Mon, Feb 7, 2022 at 10:26 PM Song Liu [off-list ref] wrote:

quoted

Instead of BUG_ON(), fail gracefully and return orig_prog.

Fixes: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Signed-off-by: Song Liu <song@kernel.org>
---
arch/x86/net/bpf_jit_comp.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 643f38b91e30..08e8fd8f954a 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c

@@ -2380,7 +2380,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
                        *
                        * Both cases are serious bugs that we should not continue.

I tweaked that comment a bit, since it's no longer accurate and
pushed to bpf-next.
Thanks!

Thanks for the fix! I had that in mind initially, but forgot about it
when I got to the keyboard. 

Song