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utils: safer str_to_long

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Make str_to_long more defensive against malformed content, since this
function runs on user (cmd line) input on x86. The input is from boot
time, i.e. trusted, but the function should still be memory safe.

This change does not fix overflow issues which may still lead to
undefined behaviour.

Signed-off-by: Gerwin Klein <gerwin.klein@proofcraft.systems>
This commit is contained in:
Gerwin Klein
2024-09-01 10:47:11 +01:00
parent ff3e7ff93e
commit 8f88c958fc
1 changed files with 10 additions and 5 deletions
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15
src/util.c
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@@ -106,18 +106,23 @@ long PURE str_to_long(const char *str)
long val = 0;
char c;
/*check for "0x" */
/* NULL ptr and empty str */
if (str == NULL || *str == 0) {
return -1;
}
/* check for "0x", *(str + 1) may be 0, but must be allocated since str is not empty */
if (*str == '0' && (*(str + 1) == 'x' || *(str + 1) == 'X')) {
base = 16;
str += 2;
/* '0x' on its own is malformed */
if (*str == 0) {
return -1;
}
} else {
base = 10;
}
if (!*str) {
return -1;
}
c = *str;
while (c != '\0') {
res = char_to_long(c);