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bpf: Fix print_reg_state's constant scalar dump

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print_reg_state() should not consider adding reg->off to reg->var_off.value
when dumping scalars. Scalars can be produced with reg->off != 0 through
BPF_ADD_CONST, and thus as-is this can skew the register log dump.

Fixes: 98d7ca374b ("bpf: Track delta between "linked" registers.")
Reported-by: Nathaniel Theis <nathaniel.theis@nccgroup.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241016134913.32249-2-daniel@iogearbox.net
This commit is contained in:
Daniel Borkmann 2024-10-16 15:49:12 +02:00 committed by Andrii Nakryiko
parent 3878ae04e9
commit 3e9e708757
1 changed files with 1 additions and 2 deletions
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3
kernel/bpf/log.c
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@ -688,8 +688,7 @@ static void print_reg_state(struct bpf_verifier_env *env,
if (t == SCALAR_VALUE && reg->precise)
verbose(env, "P");
if (t == SCALAR_VALUE && tnum_is_const(reg->var_off)) {
/* reg->off should be 0 for SCALAR_VALUE */
verbose_snum(env, reg->var_off.value + reg->off);
verbose_snum(env, reg->var_off.value);
return;
}