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Remove broken check in var_unserializer #13852

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Merged
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Apr 3, 2024
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Remove broken check in var_unserializer #13852

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5 changes: 0 additions & 5 deletions ext/standard/var_unserializer.re
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Original file line number Diff line number Diff line change
Expand Up @@ -326,11 +326,6 @@ static zend_string *unserialize_str(const unsigned char **p, size_t len, size_t
zend_string *str = zend_string_safe_alloc(1, len, 0, 0);
unsigned char *end = *(unsigned char **)p+maxlen;

if (end < *p) {
zend_string_efree(str);
return NULL;
}
Comment on lines -329 to -332
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@arnaud-lb arnaud-lb Apr 2, 2024 •
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This may not break anything that wasn't already broken because this was optimized out by the compiler, but I would prefer if we fixed this check instead of simply removing it

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@nielsdos nielsdos Apr 2, 2024 •
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The intention of the check seems to be to see if maxlen wraps around the address space.
I don't think that's possible, given that maxlen = max - YYCURSOR; and the fact that max is the pointer to the end of the input string.
So I'm not sure what you want me to replace this check with?

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You are right. I was blindly assuming that maxlen was possibly user-controlled. Looking at the history this check made more sense at some point, but now it can be removed.

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This is out of scope, but we could pass max directly to this function, maybe via UNSERIALIZE_PASSTHRU/UNSERIALIZE_PARAMETER.


for (i = 0; i < len; i++) {
if (*p >= end) {
zend_string_efree(str);
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