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Implement reallocarray()

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Stateless and I stumbled upon this issue while discussing the
semantics of read, accepting a size_t but only being able to return
ssize_t, effectively lacking the ability to report successful
reads > SSIZE_MAX.
The discussion went along and we came to the topic of input-based
memory allocations. Basically, it was possible for the argument
to a memory-allocation-function to overflow, leading to a segfault
later.
The OpenBSD-guys came up with the ingenious reallocarray-function,
and I implemented it as ereallocarray, which automatically returns
on error.
Read more about it here[0].

A simple testcase is this (courtesy to stateless):
$ sbase-strings -n (2^(32|64) / 4)

This will segfault before this patch and properly return an OOM-
situation afterwards (thanks to the overflow-check in reallocarray).

[0]: http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/calloc.3
This commit is contained in:
FRIGN
2015-03-10 21:16:21 +01:00
parent 066a0306a1
commit 3b825735d8
14 changed files with 84 additions and 27 deletions
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6
ls.c
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@@ -217,7 +217,7 @@ lsdir(const char *path)
mkent(&ent, d->d_name, Fflag || lflag || pflag || iflag || Rflag, Lflag);
ls(&ent, Rflag);
} else {
ents = erealloc(ents, ++n * sizeof(*ents));
ents = ereallocarray(ents, ++n, sizeof(*ents));
name = p = estrdup(d->d_name);
if (qflag) {
q = d->d_name;
@@ -269,7 +269,7 @@ usage(void)
int
main(int argc, char *argv[])
{
struct entry *ents;
struct entry *ents = NULL;
size_t i;
ARGBEGIN {
@@ -341,7 +341,7 @@ main(int argc, char *argv[])
if (argc == 0)
*--argv = ".", argc++;
ents = emalloc(argc * sizeof(*ents));
ents = ereallocarray(ents, argc, sizeof(*ents));
for (i = 0; i < argc; i++)
mkent(&ents[i], argv[i], 1, Hflag || Lflag);