1 files changed, 25 insertions, 28 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 0e2da8695f8e..6e48c3a43599 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2293,12 +2293,17 @@ static void layout_symtab(struct module *mod, struct load_info *info)
 	src = (void *)info->hdr + symsect->sh_offset;
 	nsrc = symsect->sh_size / sizeof(*src);
 
+	/* strtab always starts with a nul, so offset 0 is the empty string. */
+	strtab_size = 1;
+
 	/* Compute total space required for the core symbols' strtab. */
-	for (ndst = i = strtab_size = 1; i < nsrc; ++i, ++src)
-		if (is_core_symbol(src, info->sechdrs, info->hdr->e_shnum)) {
-			strtab_size += strlen(&info->strtab[src->st_name]) + 1;
+	for (ndst = i = 0; i < nsrc; i++) {
+		if (i == 0 ||
+		    is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) {
+			strtab_size += strlen(&info->strtab[src[i].st_name])+1;
 			ndst++;
 		}
+	}
 
 	/* Append room for core symbols at end of core part. */
 	info->symoffs = ALIGN(mod->core_size, symsect->sh_addralign ?: 1);
@@ -2332,15 +2337,15 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
 	mod->core_symtab = dst = mod->module_core + info->symoffs;
 	mod->core_strtab = s = mod->module_core + info->stroffs;
 	src = mod->symtab;
-	*dst = *src;
 	*s++ = 0;
-	for (ndst = i = 1; i < mod->num_symtab; ++i, ++src) {
-		if (!is_core_symbol(src, info->sechdrs, info->hdr->e_shnum))
-			continue;
-
-		dst[ndst] = *src;
-		dst[ndst++].st_name = s - mod->core_strtab;
-		s += strlcpy(s, &mod->strtab[src->st_name], KSYM_NAME_LEN) + 1;
+	for (ndst = i = 0; i < mod->num_symtab; i++) {
+		if (i == 0 ||
+		    is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) {
+			dst[ndst] = src[i];
+			dst[ndst++].st_name = s - mod->core_strtab;
+			s += strlcpy(s, &mod->strtab[src[i].st_name],
+				     KSYM_NAME_LEN) + 1;
+		}
 	}
 	mod->core_num_syms = ndst;
 }
@@ -2421,25 +2426,17 @@ static inline void kmemleak_load_module(const struct module *mod,
 
 #ifdef CONFIG_MODULE_SIG
 static int module_sig_check(struct load_info *info,
-			    const void *mod, unsigned long *len)
+			    const void *mod, unsigned long *_len)
 {
 	int err = -ENOKEY;
-	const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
-	const void *p = mod, *end = mod + *len;
-
-	/* Poor man's memmem. */
-	while ((p = memchr(p, MODULE_SIG_STRING[0], end - p))) {
-		if (p + markerlen > end)
-			break;
-
-		if (memcmp(p, MODULE_SIG_STRING, markerlen) == 0) {
-			const void *sig = p + markerlen;
-			/* Truncate module up to signature. */
-			*len = p - mod;
-			err = mod_verify_sig(mod, *len, sig, end - sig);
-			break;
-		}
-		p++;
+	unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
+	unsigned long len = *_len;
+
+	if (len > markerlen &&
+	    memcmp(mod + len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
+		/* We truncate the module to discard the signature */
+		*_len -= markerlen;
+		err = mod_verify_sig(mod, _len);
 	}
 
 	if (!err) {