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authorAlexei Starovoitov <ast@fb.com>2016-09-01 18:37:23 -0700
committerDavid S. Miller <davem@davemloft.net>2016-09-02 10:46:44 -0700
commitfdc15d388d600d5a1599e14c700af105a5b60761 (patch)
tree6c197edb2fc2040e8069ff372baebcda5770ba25 /kernel/bpf
parent0515e5999a466dfe6e1924f460da599bb6821487 (diff)
bpf: perf_event progs should only use preallocated maps
Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use preallocated hash maps, since doing memory allocation in overflow_handler can crash depending on where nmi got triggered. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf')
-rw-r--r--kernel/bpf/verifier.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c1c9e441f0f5..48c2705db22c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2511,6 +2511,20 @@ process_bpf_exit:
return 0;
}
+static int check_map_prog_compatibility(struct bpf_map *map,
+ struct bpf_prog *prog)
+
+{
+ if (prog->type == BPF_PROG_TYPE_PERF_EVENT &&
+ (map->map_type == BPF_MAP_TYPE_HASH ||
+ map->map_type == BPF_MAP_TYPE_PERCPU_HASH) &&
+ (map->map_flags & BPF_F_NO_PREALLOC)) {
+ verbose("perf_event programs can only use preallocated hash map\n");
+ return -EINVAL;
+ }
+ return 0;
+}
+
/* look for pseudo eBPF instructions that access map FDs and
* replace them with actual map pointers
*/
@@ -2518,7 +2532,7 @@ static int replace_map_fd_with_map_ptr(struct verifier_env *env)
{
struct bpf_insn *insn = env->prog->insnsi;
int insn_cnt = env->prog->len;
- int i, j;
+ int i, j, err;
for (i = 0; i < insn_cnt; i++, insn++) {
if (BPF_CLASS(insn->code) == BPF_LDX &&
@@ -2562,6 +2576,12 @@ static int replace_map_fd_with_map_ptr(struct verifier_env *env)
return PTR_ERR(map);
}
+ err = check_map_prog_compatibility(map, env->prog);
+ if (err) {
+ fdput(f);
+ return err;
+ }
+
/* store map pointer inside BPF_LD_IMM64 instruction */
insn[0].imm = (u32) (unsigned long) map;
insn[1].imm = ((u64) (unsigned long) map) >> 32;