From 08e878a94b3a64ee7768a2e1b8696369d69d32c2 Mon Sep 17 00:00:00 2001 From: KP Singh Date: Mon, 1 Jun 2026 17:02:47 +0200 Subject: [PATCH 1/2] selftests/bpf: Adjust verifier_map_ptr for the map's excl field commit 38498c0ebacd54dbaac3513a548a13f1a8455c4e upstream. Adding the u32 excl field at offset 32 of struct bpf_map right after the sha[SHA256_DIGEST_SIZE] hash shifts the ops pointer from offset 32 to 40. Therefore, fix up the test case. # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_map_ptr [...] #637/1 verifier_map_ptr/bpf_map_ptr: read with negative offset rejected:OK #637/2 verifier_map_ptr/bpf_map_ptr: read with negative offset rejected @unpriv:OK #637/3 verifier_map_ptr/bpf_map_ptr: write rejected:OK #637/4 verifier_map_ptr/bpf_map_ptr: write rejected @unpriv:OK #637/5 verifier_map_ptr/bpf_map_ptr: read non-existent field rejected:OK #637/6 verifier_map_ptr/bpf_map_ptr: read non-existent field rejected @unpriv:OK #637/7 verifier_map_ptr/bpf_map_ptr: read ops field accepted:OK #637/8 verifier_map_ptr/bpf_map_ptr: read ops field accepted @unpriv:OK [...] Summary: 2/18 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: KP Singh Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260601150248.394863-7-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Signed-off-by: Shung-Hsi Yu --- tools/testing/selftests/bpf/progs/verifier_map_ptr.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/verifier_map_ptr.c b/tools/testing/selftests/bpf/progs/verifier_map_ptr.c index e2767d27d8aaf..d8e822d1a8bab 100644 --- a/tools/testing/selftests/bpf/progs/verifier_map_ptr.c +++ b/tools/testing/selftests/bpf/progs/verifier_map_ptr.c @@ -70,13 +70,15 @@ __naked void bpf_map_ptr_write_rejected(void) : __clobber_all); } -/* The first element of struct bpf_map is a SHA256 hash of 32 bytes, accessing - * into this array is valid. The opts field is now at offset 33. +/* + * struct bpf_map starts with the SHA256 hash sha[32] at offset 0 (a readable + * byte array), followed by the u32 excl field at offset 32. Reading a u32 at + * offset 33 runs past the end of excl and is rejected. */ SEC("socket") __description("bpf_map_ptr: read non-existent field rejected") __failure -__msg("cannot access ptr member ops with moff 32 in struct bpf_map with off 33 size 4") +__msg("access beyond the end of member excl (mend:36) in struct bpf_map with off 33 size 4") __failure_unpriv __msg_unpriv("access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN") __flag(BPF_F_ANY_ALIGNMENT) From 38ce453958684cc7435b502e168481baf3093ab0 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Tue, 2 Jun 2026 15:30:51 +0200 Subject: [PATCH 2/2] selftests/bpf: Keep verifier_map_ptr exercising ops pointer access commit 082c412097716b93ff1365689fc4ddcd1ce8296f upstream. sashiko complained that 38498c0ebacd ("selftests/bpf: Adjust verifier_map_ptr for the map's excl field") would slightly decrease the test coverage given before the test was against the verifier rejecting the ops pointer. Recover the old test with the right offsets and add the existing one as an additional test case. # LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t verifier_map_ptr [ 1.672932] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #637/1 verifier_map_ptr/bpf_map_ptr: read with negative offset rejected:OK #637/2 verifier_map_ptr/bpf_map_ptr: read with negative offset rejected @unpriv:OK #637/3 verifier_map_ptr/bpf_map_ptr: write rejected:OK #637/4 verifier_map_ptr/bpf_map_ptr: write rejected @unpriv:OK #637/5 verifier_map_ptr/bpf_map_ptr: read non-existent field rejected:OK #637/6 verifier_map_ptr/bpf_map_ptr: read non-existent field rejected @unpriv:OK #637/7 verifier_map_ptr/bpf_map_ptr: read beyond excl field rejected:OK #637/8 verifier_map_ptr/bpf_map_ptr: read beyond excl field rejected @unpriv:OK #637/9 verifier_map_ptr/bpf_map_ptr: read ops field accepted:OK #637/10 verifier_map_ptr/bpf_map_ptr: read ops field accepted @unpriv:OK #637/11 verifier_map_ptr/bpf_map_ptr: r = 0, map_ptr = map_ptr + r:OK #637/12 verifier_map_ptr/bpf_map_ptr: r = 0, map_ptr = map_ptr + r @unpriv:OK #637/13 verifier_map_ptr/bpf_map_ptr: r = 0, r = r + map_ptr:OK #637/14 verifier_map_ptr/bpf_map_ptr: r = 0, r = r + map_ptr @unpriv:OK #637 verifier_map_ptr:OK [...] Summary: 2/20 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20260602133052.423725-4-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov Signed-off-by: Shung-Hsi Yu --- .../selftests/bpf/progs/verifier_map_ptr.c | 34 ++++++++++++++++--- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/verifier_map_ptr.c b/tools/testing/selftests/bpf/progs/verifier_map_ptr.c index d8e822d1a8bab..1661936598703 100644 --- a/tools/testing/selftests/bpf/progs/verifier_map_ptr.c +++ b/tools/testing/selftests/bpf/progs/verifier_map_ptr.c @@ -72,17 +72,43 @@ __naked void bpf_map_ptr_write_rejected(void) /* * struct bpf_map starts with the SHA256 hash sha[32] at offset 0 (a readable - * byte array), followed by the u32 excl field at offset 32. Reading a u32 at - * offset 33 runs past the end of excl and is rejected. + * byte array), the u32 excl field at offset 32, and the ops pointer at offset + * 40. Reading a u32 at offset 41 reaches into the middle of the ops pointer, + * i.e. a partial pointer access, which is rejected. */ SEC("socket") __description("bpf_map_ptr: read non-existent field rejected") __failure -__msg("access beyond the end of member excl (mend:36) in struct bpf_map with off 33 size 4") +__msg("cannot access ptr member ops with moff 40 in struct bpf_map with off 41 size 4") __failure_unpriv __msg_unpriv("access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN") __flag(BPF_F_ANY_ALIGNMENT) __naked void read_non_existent_field_rejected(void) +{ + asm volatile (" \ + r6 = 0; \ + r1 = %[map_array_48b] ll; \ + r6 = *(u32*)(r1 + 41); \ + r0 = 1; \ + exit; \ +" : + : __imm_addr(map_array_48b) + : __clobber_all); +} + +/* + * The u32 excl field spans offsets 32..35 (mend 36). Reading a u32 at offset + * 33 starts inside excl but extends past its end, which the verifier rejects + * as an out-of-bounds scalar access. + */ +SEC("socket") +__description("bpf_map_ptr: read beyond excl field rejected") +__failure +__msg("access beyond the end of member excl (mend:36) in struct bpf_map with off 33 size 4") +__failure_unpriv +__msg_unpriv("access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN") +__flag(BPF_F_ANY_ALIGNMENT) +__naked void read_beyond_excl_field_rejected(void) { asm volatile (" \ r6 = 0; \ @@ -105,7 +131,7 @@ __naked void ptr_read_ops_field_accepted(void) asm volatile (" \ r6 = 0; \ r1 = %[map_array_48b] ll; \ - r6 = *(u64*)(r1 + 0); \ + r6 = *(u64*)(r1 + 40); \ r0 = 1; \ exit; \ " :