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| author |   Alexei Starovoitov <ast@kernel.org> | 2021-11-01 15:21:51 -0700 |
|---|---|---|
| committer |   Andrii Nakryiko <andrii@kernel.org> | 2021-11-01 18:05:11 -0700 |
| commit | b9979db8340154526d9ab38a1883d6f6ba9b6d47 (patch) | |
| tree | 41177055a06e0ac1de0edaab7b2cc3cec8cb2864 /kernel/bpf | |
| parent | selftests/bpf: Fix also no-alu32 strobemeta selftest (diff) | |
| download | linux-dev-b9979db8340154526d9ab38a1883d6f6ba9b6d47.tar.xz linux-dev-b9979db8340154526d9ab38a1883d6f6ba9b6d47.zip | |
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
Before this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff))
After this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1))
While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1
and call __reg_combine_64_into_32(true_reg).
Without the fix it would not pass the condition:
if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value))
since umin_value == 0 at this point.
Before commit 10bf4e83167c the umin was incorrectly ingored.
The commit 10bf4e83167c fixed the correctness issue, but pessimized
propagation of 64-bit min max into 32-bit min max and corresponding var_off.
Fixes: 10bf4e83167c ("bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-1-alexei.starovoitov@gmail.com
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3c8aa7df1773..29671ed49ee8 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1425,7 +1425,7 @@ static bool __reg64_bound_s32(s64 a) static bool __reg64_bound_u32(u64 a) { - return a > U32_MIN && a < U32_MAX; + return a >= U32_MIN && a <= U32_MAX; } static void __reg_combine_64_into_32(struct bpf_reg_state *reg) |