libkmod: Unify crclen calculation in ELF parser

Whenever sizeof(mv->crc) is used, it's called crclen, not offcrc.
Move retrieval of field sizes into its own function.
Prepare this as a cleanup for easier auditing.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/222
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>

diff --git a/libkmod/libkmod-elf.c b/libkmod/libkmod-elf.c
index 0a23f9180414717e70a80995cf84e6eba053f118..b9e4910d3cd693c0a94104433e3f1fdd853721bc 100644 (file)
--- a/libkmod/libkmod-elf.c
+++ b/libkmod/libkmod-elf.c
@@ -460,22 +460,34 @@ int kmod_elf_get_strings(const struct kmod_elf *elf, const char *section, char *
        return count;
 }
 
+static inline void elf_get_modversion_lengths(const struct kmod_elf *elf, size_t *verlen,
+                                             size_t *crclen)
+{
+       assert_cc(sizeof(struct kmod_modversion64) == sizeof(struct kmod_modversion32));
+
+       if (elf->x32) {
+               struct kmod_modversion32 *mv;
+
+               *verlen = sizeof(*mv);
+               *crclen = sizeof(mv->crc);
+       } else {
+               struct kmod_modversion64 *mv;
+
+               *verlen = sizeof(*mv);
+               *crclen = sizeof(mv->crc);
+       }
+}
+
 /* array will be allocated with strings in a single malloc, just free *array */
 int kmod_elf_get_modversions(const struct kmod_elf *elf, struct kmod_modversion **array)
 {
-       size_t off, offcrc, slen;
+       size_t off, crclen, slen, verlen;
        uint64_t sec_off, size;
        struct kmod_modversion *a;
        char *itr;
        int i, count, err;
-#define MODVERSION_SEC_SIZE (sizeof(struct kmod_modversion64))
 
-       assert_cc(sizeof(struct kmod_modversion64) == sizeof(struct kmod_modversion32));
-
-       if (elf->x32)
-               offcrc = sizeof(uint32_t);
-       else
-               offcrc = sizeof(uint64_t);
+       elf_get_modversion_lengths(elf, &verlen, &crclen);
 
        *array = NULL;
 
@@ -486,16 +498,16 @@ int kmod_elf_get_modversions(const struct kmod_elf *elf, struct kmod_modversion
        if (size == 0)
                return 0;
 
-       if (size % MODVERSION_SEC_SIZE != 0)
+       if (size % verlen != 0)
                return -EINVAL;
 
-       count = size / MODVERSION_SEC_SIZE;
+       count = size / verlen;
 
        off = sec_off;
        slen = 0;
 
-       for (i = 0; i < count; i++, off += MODVERSION_SEC_SIZE) {
-               const char *symbol = elf_get_mem(elf, off + offcrc);
+       for (i = 0; i < count; i++, off += verlen) {
+               const char *symbol = elf_get_mem(elf, off + crclen);
 
                if (symbol[0] == '.')
                        symbol++;
@@ -510,9 +522,9 @@ int kmod_elf_get_modversions(const struct kmod_elf *elf, struct kmod_modversion
        itr = (char *)(a + count);
        off = sec_off;
 
-       for (i = 0; i < count; i++, off += MODVERSION_SEC_SIZE) {
-               uint64_t crc = elf_get_uint(elf, off, offcrc);
-               const char *symbol = elf_get_mem(elf, off + offcrc);
+       for (i = 0; i < count; i++, off += verlen) {
+               uint64_t crc = elf_get_uint(elf, off, crclen);
+               const char *symbol = elf_get_mem(elf, off + crclen);
                size_t symbollen;
 
                if (symbol[0] == '.')
@@ -905,15 +917,7 @@ static int kmod_elf_crc_find(const struct kmod_elf *elf, uint64_t off,
        size_t verlen, crclen;
        uint64_t i;
 
-       if (elf->x32) {
-               struct kmod_modversion32 *mv;
-               verlen = sizeof(*mv);
-               crclen = sizeof(mv->crc);
-       } else {
-               struct kmod_modversion64 *mv;
-               verlen = sizeof(*mv);
-               crclen = sizeof(mv->crc);
-       }
+       elf_get_modversion_lengths(elf, &verlen, &crclen);
 
        for (i = 0; i < versionslen; i += verlen) {
                const char *symbol = elf_get_mem(elf, off + i + crclen);
@@ -953,15 +957,7 @@ int kmod_elf_get_dependency_symbols(const struct kmod_elf *elf,
                verlen = 0;
                crclen = 0;
        } else {
-               if (elf->x32) {
-                       struct kmod_modversion32 *mv;
-                       verlen = sizeof(*mv);
-                       crclen = sizeof(mv->crc);
-               } else {
-                       struct kmod_modversion64 *mv;
-                       verlen = sizeof(*mv);
-                       crclen = sizeof(mv->crc);
-               }
+               elf_get_modversion_lengths(elf, &verlen, &crclen);
                if (versionslen % verlen != 0) {
                        ELFDBG(elf,
                               "unexpected __versions of length %" PRIu64