imrcpan/erofs-linux
1
0 Fork 0
mirror of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs.git synced 2026-10-29 13:23:23 +01:00
Code Issues Packages Projects Releases Wiki Activity

bpf: detect non null pointer with register operand in JEQ/JNE.

Browse Source 
This patch adds support to validate a pointer as not null when its
value is compared to a register whose value the verifier knows to be
null.
Initial pattern only verifies against an immediate operand.

Signed-off-by: Cupertino Miranda <[email protected]>
Cc: David Faust  <[email protected]>
Cc: Jose Marchesi  <[email protected]>
Cc: Elena Zannoni  <[email protected]>
Acked-by: Eduard Zingerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
This commit is contained in:
Cupertino Miranda authored and Alexei Starovoitov committed 2026-03-10 11:51:18 -07:00
1 parent bd2e02e3c9
commit 2f4cb53eed
1 file changed
+6 -3
Download Patch File Download Diff File Expand all files Collapse all files
kernel/bpf/verifier.c
+6 -3
View File
@@ -17678,12 +17678,15 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
}
/* detect if R == 0 where R is returned from bpf_map_lookup_elem().
* Also does the same detection for a register whose the value is
* known to be 0.
* NOTE: these optimizations below are related with pointer comparison
* which will never be JMP32.
*/
if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K &&
insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
type_may_be_null(dst_reg->type)) {
if (!is_jmp32 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
type_may_be_null(dst_reg->type) &&
((BPF_SRC(insn->code) == BPF_K && insn->imm == 0) ||
(BPF_SRC(insn->code) == BPF_X && register_is_null(src_reg)))) {
/* Mark all identical registers in each branch as either
* safe or unknown depending R == 0 or R != 0 conditional.
*/