From 19fa57745a67f5aebb526c2f7b9d1b9aaad552f3 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 1 Mar 2024 08:52:24 +0100 Subject: [PATCH] bpf: Take return from set_memory_ro() into account with bpf_prog_lock_ro() 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 Cc: linux-hardening@vger.kernel.org Reviewed-by: Kees Cook --- 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 36cc29a2934cb..7dd59bccaeecd 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 71c459a51d9e1..c49619ef55d01 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 1c34b91b95838..6ec134f76a11c 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]); }