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librb/src/crypt.c: rb_sha*_crypt_r: avoid UB pointer math

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This code is doing (foo - (char*)0) to convert foo from a pointer
value into a numeric value. Unfortunately, this is undefined
behaviour, which clang-14 is now warning about [1].

Cast to uintptr_t instead. Same result, but well-defined.

[1] cf. commit 0302f1532b
This commit is contained in:
Aaron Jones 2022-08-24 23:51:14 +00:00 committed by Doug Freed
parent 0302f1532b
commit ae510cce12
1 changed files with 8 additions and 8 deletions
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16
librb/src/crypt.c
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@ -1497,20 +1497,20 @@ static char *rb_sha256_crypt_r(const char *key, const char *salt, char *buffer,
salt_len = MIN(strcspn(salt, "$"), SHA256_SALT_LEN_MAX); salt_len = MIN(strcspn(salt, "$"), SHA256_SALT_LEN_MAX);
key_len = strlen(key); key_len = strlen(key);
if ((key - (char *)0) % __alignof__(uint32_t) != 0) if (((uintptr_t) key) % __alignof__(uint32_t) != 0)
{ {
char *tmp = (char *)alloca(key_len + __alignof__(uint32_t)); char *tmp = (char *)alloca(key_len + __alignof__(uint32_t));
key = copied_key = key = copied_key =
memcpy(tmp + __alignof__(uint32_t) memcpy(tmp + __alignof__(uint32_t)
- (tmp - (char *)0) % __alignof__(uint32_t), key, key_len); - ((uintptr_t) tmp) % __alignof__(uint32_t), key, key_len);
} }
if ((salt - (char *)0) % __alignof__(uint32_t) != 0) if (((uintptr_t) salt) % __alignof__(uint32_t) != 0)
{ {
char *tmp = (char *)alloca(salt_len + __alignof__(uint32_t)); char *tmp = (char *)alloca(salt_len + __alignof__(uint32_t));
salt = copied_salt = salt = copied_salt =
memcpy(tmp + __alignof__(uint32_t) memcpy(tmp + __alignof__(uint32_t)
- (tmp - (char *)0) % __alignof__(uint32_t), salt, salt_len); - ((uintptr_t) tmp) % __alignof__(uint32_t), salt, salt_len);
} }
/* Prepare for the real work. */ /* Prepare for the real work. */
@ -2075,20 +2075,20 @@ static char *rb_sha512_crypt_r(const char *key, const char *salt, char *buffer,
salt_len = MIN(strcspn(salt, "$"), SHA512_SALT_LEN_MAX); salt_len = MIN(strcspn(salt, "$"), SHA512_SALT_LEN_MAX);
key_len = strlen(key); key_len = strlen(key);
if ((key - (char *)0) % __alignof__(uint64_t) != 0) if (((uintptr_t) key) % __alignof__(uint64_t) != 0)
{ {
char *tmp = (char *)alloca(key_len + __alignof__(uint64_t)); char *tmp = (char *)alloca(key_len + __alignof__(uint64_t));
key = copied_key = key = copied_key =
memcpy(tmp + __alignof__(uint64_t) memcpy(tmp + __alignof__(uint64_t)
- (tmp - (char *)0) % __alignof__(uint64_t), key, key_len); - ((uintptr_t) tmp) % __alignof__(uint64_t), key, key_len);
} }
if ((salt - (char *)0) % __alignof__(uint64_t) != 0) if (((uintptr_t) salt) % __alignof__(uint64_t) != 0)
{ {
char *tmp = (char *)alloca(salt_len + __alignof__(uint64_t)); char *tmp = (char *)alloca(salt_len + __alignof__(uint64_t));
salt = copied_salt = salt = copied_salt =
memcpy(tmp + __alignof__(uint64_t) memcpy(tmp + __alignof__(uint64_t)
- (tmp - (char *)0) % __alignof__(uint64_t), salt, salt_len); - ((uintptr_t) tmp) % __alignof__(uint64_t), salt, salt_len);
} }
/* Prepare for the real work. */ /* Prepare for the real work. */