This is a note to let you know that I've just added the patch titled
bpf: fix bpf_tail_call() x64 JIT
to the 4.13-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-fix-bpf_tail_call-x64-jit.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Oct 9 09:32:35 CEST 2017
From: Alexei Starovoitov <ast@xxxxxx>
Date: Tue, 3 Oct 2017 15:37:20 -0700
Subject: bpf: fix bpf_tail_call() x64 JIT
From: Alexei Starovoitov <ast@xxxxxx>
[ Upstream commit 90caccdd8cc0215705f18b92771b449b01e2474a ]
- bpf prog_array just like all other types of bpf array accepts 32-bit index.
Clarify that in the comment.
- fix x64 JIT of bpf_tail_call which was incorrectly loading 8 instead of 4 bytes
- tighten corresponding check in the interpreter to stay consistent
The JIT bug can be triggered after introduction of BPF_F_NUMA_NODE flag
in commit 96eabe7a40aa in 4.14. Before that the map_flags would stay zero and
though JIT code is wrong it will check bounds correctly.
Hence two fixes tags. All other JITs don't have this problem.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Fixes: 96eabe7a40aa ("bpf: Allow selecting numa node during map creation")
Fixes: b52f00e6a715 ("x86: bpf_jit: implement bpf_tail_call() helper")
Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: Martin KaFai Lau <kafai@xxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 4 ++--
include/uapi/linux/bpf.h | 2 +-
kernel/bpf/core.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -282,9 +282,9 @@ static void emit_bpf_tail_call(u8 **ppro
/* if (index >= array->map.max_entries)
* goto out;
*/
- EMIT4(0x48, 0x8B, 0x46, /* mov rax, qword ptr [rsi + 16] */
+ EMIT2(0x89, 0xD2); /* mov edx, edx */
+ EMIT3(0x39, 0x56, /* cmp dword ptr [rsi + 16], edx */
offsetof(struct bpf_array, map.max_entries));
- EMIT3(0x48, 0x39, 0xD0); /* cmp rax, rdx */
#define OFFSET1 47 /* number of bytes to jump */
EMIT2(X86_JBE, OFFSET1); /* jbe out */
label1 = cnt;
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -294,7 +294,7 @@ union bpf_attr {
* jump into another BPF program
* @ctx: context pointer passed to next program
* @prog_array_map: pointer to map which type is BPF_MAP_TYPE_PROG_ARRAY
- * @index: index inside array that selects specific program to run
+ * @index: 32-bit index inside array that selects specific program to run
* Return: 0 on success or negative error
*
* int bpf_clone_redirect(skb, ifindex, flags)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1010,7 +1010,7 @@ select_insn:
struct bpf_map *map = (struct bpf_map *) (unsigned long) BPF_R2;
struct bpf_array *array = container_of(map, struct bpf_array, map);
struct bpf_prog *prog;
- u64 index = BPF_R3;
+ u32 index = BPF_R3;
if (unlikely(index >= array->map.max_entries))
goto out;
Patches currently in stable-queue which might be from ast@xxxxxx are
queue-4.13/bpf-fix-bpf_tail_call-x64-jit.patch