bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode
[ Upstream commit e8742081 ] syzbot reported uninit memory usages during map_{lookup,delete}_elem. ========== BUG: KMSAN: uninit-value in __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline] BUG: KMSAN: uninit-value in dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796 __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline] dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796 ____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline] bpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997 __bpf_prog_run256+0xb5/0xe0 kernel/bpf/core.c:2237 ========== The reproducer should be in the interpreter mode. The C reproducer is trying to run the following bpf prog: 0: (18) r0 = 0x0 2: (18) r1 = map[id:49] 4: (b7) r8 = 16777216 5: (7b) *(u64 *)(r10 -8) = r8 6: (bf) r2 = r10 7: (07) r2 += -229 ^^^^^^^^^^ 8: (b7) r3 = 8 9: (b7) r4 = 0 10: (85) call dev_map_lookup_elem#1543472 11: (95) exit It is due to the "void *key" (r2) passed to the helper. bpf allows uninit stack memory access for bpf prog with the right privileges. This patch uses kmsan_unpoison_memory() to mark the stack as initialized. This should address different syzbot reports on the uninit "void *key" argument during map_{lookup,delete}_elem. Reported-by:<syzbot+603bcd9b0bf1d94dbb9b@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/bpf/000000000000f9ce6d061494e694@google.com/ Reported-by:
<syzbot+eb02dc7f03dce0ef39f3@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/bpf/000000000000a5c69c06147c2238@google.com/ Reported-by:
<syzbot+b4e65ca24fd4d0c734c3@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/bpf/000000000000ac56fb06143b6cfa@google.com/ Reported-by:
<syzbot+d2b113dc9fea5e1d2848@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/bpf/0000000000000d69b206142d1ff7@google.com/ Reported-by:
<syzbot+1a3cf6f08d68868f9db3@syzkaller.appspotmail.com> Closes: https://lore.kernel.org/bpf/0000000000006f876b061478e878@google.com/ Tested-by:
<syzbot+1a3cf6f08d68868f9db3@syzkaller.appspotmail.com> Suggested-by:
Yonghong Song <yonghong.song@linux.dev> Suggested-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20240328185801.1843078-1-martin.lau@linux.dev Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
Sasha Levin <sashal@kernel.org>
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