xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

bpf: fix check for attempt to corrupt spilled pointer

Browse Source 
[ 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: 27113c59b6d0 ("bpf: Check the other end of slot_type for STACK_SPILL")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Andrii Nakryiko
2023-12-05 10:42:41 -08:00
committed by Greg Kroah-Hartman
parent 7e98bbeb07
commit 2757f17972
1 changed files with 1 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
kernel/bpf/verifier.c
View File

@@ -2493,7 +2493,7 @@ 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 * so it's aligned access and [off, off + size) are within stack limits
*/ */
if (!env->allow_ptr_leaks && if (!env->allow_ptr_leaks &&
state->stack[spi].slot_type[0] == STACK_SPILL && is_spilled_reg(&state->stack[spi]) &&
size != BPF_REG_SIZE) { size != BPF_REG_SIZE) {
verbose(env, "attempt to corrupt spilled pointer on stack\n"); verbose(env, "attempt to corrupt spilled pointer on stack\n");
return -EACCES; return -EACCES;