Commit b6ff704c authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Pu Lehui
Browse files

bpf: fix check for attempt to corrupt spilled pointer 

stable inclusion
from stable-v5.10.209
commit 2757f17972d87773b3677777f5682510f13c66ef
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I93ED4
CVE: CVE-2023-52462

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=2757f17972d87773b3677777f5682510f13c66ef



--------------------------------

[ Upstream commit ab125ed3ec1c10ccc36bc98c7a4256ad114a3dae ]

When register is spilled onto a stack as a 1/2/4-byte register, we set
slot_type[BPF_REG_SIZE - 1] (plus potentially few more below it,
depending on actual spill size). So to check if some stack slot has
spilled register we need to consult slot_type[7], not slot_type[0].

To avoid the need to remember and double-check this in the future, just
use is_spilled_reg() helper.

Fixes: 27113c59 ("bpf: Check the other end of slot_type for STACK_SPILL")
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarWang Hai <wanghai38@huawei.com>
Signed-off-by: default avatarPu Lehui <pulehui@huawei.com>
parent 183e1907

kernel/bpf/verifier.c

+1 −1
Original line number Diff line number Diff line
@@ -2500,7 +2500,7 @@ static int check_stack_write_fixed_off(struct bpf_verifier_env *env, 
	 * so it's aligned access and [off, off + size) are within stack limits

	 */

	if (!env->allow_ptr_leaks &&

	    state->stack[spi].slot_type[0] == STACK_SPILL &&

	    is_spilled_reg(&state->stack[spi]) &&

	    size != BPF_REG_SIZE) {

		verbose(env, "attempt to corrupt spilled pointer on stack\n");

		return -EACCES;