set_memory_ro() can fail, leaving memory unprotected. Check its return and take it into account as an error. Link: https://github.com/KSPP/linux/issues/7 Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: linux-hardening@xxxxxxxxxxxxxxx <linux-hardening@xxxxxxxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> --- Note: next patch is autonomous, it is sent as a follow-up of this one to minimize risk of conflict on filter.h because the two changes are too close to each other. v2: No modification (Just added link in patch message), patchwork discarded this series due to failed test of s390 but it seems unrelated, see https://lore.kernel.org/bpf/wvd5gzde5ejc2rzsbrtwqyof56uw5ea3rxntfrxtkdabzcuwt6@w7iczzhmay2i/T/#m2e61446f42d5dc3d78f2e0e8b7a783f15cfb109d --- include/linux/filter.h | 5 +++-- kernel/bpf/core.c | 4 +++- kernel/bpf/verifier.c | 4 +++- 3 files changed, 9 insertions(+), 4 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 36cc29a2934c..7dd59bccaeec 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -884,14 +884,15 @@ bpf_ctx_narrow_access_offset(u32 off, u32 size, u32 size_default) #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0])) -static inline void bpf_prog_lock_ro(struct bpf_prog *fp) +static inline int __must_check bpf_prog_lock_ro(struct bpf_prog *fp) { #ifndef CONFIG_BPF_JIT_ALWAYS_ON if (!fp->jited) { set_vm_flush_reset_perms(fp); - set_memory_ro((unsigned long)fp, fp->pages); + return set_memory_ro((unsigned long)fp, fp->pages); } #endif + return 0; } static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr) diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 71c459a51d9e..c49619ef55d0 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2392,7 +2392,9 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err) } finalize: - bpf_prog_lock_ro(fp); + *err = bpf_prog_lock_ro(fp); + if (*err) + return fp; /* The tail call compatibility check can only be done at * this late stage as we need to determine, if we deal diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1c34b91b9583..6ec134f76a11 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19096,7 +19096,9 @@ static int jit_subprogs(struct bpf_verifier_env *env) * bpf_prog_load will add the kallsyms for the main program. */ for (i = 1; i < env->subprog_cnt; i++) { - bpf_prog_lock_ro(func[i]); + err = bpf_prog_lock_ro(func[i]); + if (err) + goto out_free; bpf_prog_kallsyms_add(func[i]); } -- 2.43.0
