libkmod-index: protect ourselves from corrupted indexes

If index is shorter than 12 bytes, we couldn't even read its header. Go
to error handling in this case.

diff --git a/libkmod/libkmod-index.c b/libkmod/libkmod-index.c
index 4ab4ed5..a5933e2 100644 (file)
--- a/libkmod/libkmod-index.c
+++ b/libkmod/libkmod-index.c
@@ -798,12 +798,14 @@ struct index_mm *index_mm_open(struct kmod_ctx *ctx, const char *filename,
        }
 
        fstat(fd, &st);
+       if ((size_t) st.st_size < sizeof(hdr))
+               goto fail_nommap;
 
        if ((idx->mm = mmap(0, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0))
                                                        == MAP_FAILED) {
                ERR(ctx, "mmap(0, %"PRIu64", PROT_READ, %d, MAP_PRIVATE, 0): %m\n",
                                                        st.st_size, fd);
-               goto fail;
+               goto fail_nommap;
        }
 
        p = idx->mm;
@@ -833,9 +835,9 @@ struct index_mm *index_mm_open(struct kmod_ctx *ctx, const char *filename,
        return idx;
 
 fail:
+       munmap(idx->mm, st.st_size);
+fail_nommap:
        close(fd);
-       if (idx->mm != MAP_FAILED)
-               munmap(idx->mm, st.st_size);
 fail_open:
        free(idx);
        return NULL;