From: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn> mainline inclusion from mainline-v7.2-rc7 commit a4c6f804b44c5c790269b25e0e61cf4e9f117c86 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/17686 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When scalar += pointer is handled in adjust_ptr_min_max_vals(), the destination register inherits the pointer state from the source pointer. Copying only selected fields is fragile because pointer provenance is tracked by several bpf_reg_state fields. Use the caller's temporary offset register to preserve the scalar operand while replacing the destination with the full pointer state. This preserves the frame number for PTR_TO_STACK registers and keeps parent identity fields consistent. Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)") Signed-off-by: Yiyang Chen <chenyy23@mails.tsinghua.edu.cn> Tested-by: Daniel Wade <danjwade95@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Link: https://patch.msgid.link/20260729-c3-035-public-bpf-v4-v4-2-8ee297e2346b@mai... Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Conflicts: kernel/bpf/verifier.c [ctx conflicts] Signed-off-by: Pu Lehui <pulehui@huawei.com> --- kernel/bpf/verifier.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e00cb52fb480..71cc52cfaf31 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3124,11 +3124,12 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, return -EACCES; } - /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. - * The id may be overwritten later if we create a new variable offset. + /* For 'scalar += pointer', dst_reg inherits the complete pointer + * register state. Individual fields may be adjusted later by pointer + * arithmetic. Callers guarantee that below does not overwrite off_reg. */ - dst_reg->type = ptr_reg->type; - dst_reg->id = ptr_reg->id; + if (dst_reg != ptr_reg) + *dst_reg = *ptr_reg; if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) || !check_reg_sane_offset(env, ptr_reg, ptr_reg->type)) @@ -3193,7 +3194,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, } break; case BPF_SUB: - if (dst_reg == off_reg) { + if (dst_reg != ptr_reg) { /* scalar -= pointer. Creates an unknown scalar */ verbose(env, "R%d tried to subtract pointer from scalar\n", dst); @@ -3598,8 +3599,8 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env, * This is legal, but we have to reverse our * src/dest handling in computing the range */ - return adjust_ptr_min_max_vals(env, insn, - src_reg, dst_reg); + off_reg = *dst_reg; + return adjust_ptr_min_max_vals(env, insn, src_reg, &off_reg); } } else if (ptr_reg) { /* pointer += scalar */ -- 2.34.1