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Fix integer overflow in _sdsMakeRoomFor (CVE-2021-41099) #80

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Fix integer overflow in _sdsMakeRoomFor (CVE-2021-41099) #80

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5 changes: 3 additions & 2 deletions rmutil/sds.c
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Original file line number Diff line number Diff line change
Expand Up @@ -194,7 +194,7 @@ void sdsclear(sds s) {
sds sdsMakeRoomFor(sds s, size_t addlen) {
void *sh, *newsh;
size_t avail = sdsavail(s);
size_t len, newlen;
size_t len, newlen, reqlen;
char type, oldtype = s[-1] & SDS_TYPE_MASK;
int hdrlen;

Expand All @@ -203,7 +203,7 @@ sds sdsMakeRoomFor(sds s, size_t addlen) {

len = sdslen(s);
sh = (char*)s-sdsHdrSize(oldtype);
newlen = (len+addlen);
reqlen = newlen = (len+addlen);
if (newlen < SDS_MAX_PREALLOC)
newlen *= 2;
else
Expand All @@ -217,6 +217,7 @@ sds sdsMakeRoomFor(sds s, size_t addlen) {
if (type == SDS_TYPE_5) type = SDS_TYPE_8;

hdrlen = sdsHdrSize(type);
assert(hdrlen + newlen + 1 > reqlen); /* Catch size_t overflow */
if (oldtype==type) {
newsh = s_realloc(sh, hdrlen+newlen+1);
if (newsh == NULL) return NULL;
Expand Down