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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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4
printf.c
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@@ -111,7 +111,7 @@ main(int argc, char *argv[])
break;
case 'c':
unescape(arg);
rarg = emalloc((utflen(arg) + 1) * sizeof(*rarg));
rarg = ereallocarray(rarg, utflen(arg) + 1, sizeof(*rarg));
utftorunestr(arg, rarg);
efputrune(rarg, stdout, "<stdout>");
free(rarg);
@@ -125,7 +125,7 @@ main(int argc, char *argv[])
if (arg[j] == '\'' || arg[j] == '\"') {
arg += j + 1;
unescape(arg);
rarg = emalloc((utflen(arg) + 1) * sizeof(*rarg));
rarg = ereallocarray(rarg, utflen(arg) + 1, sizeof(*rarg));
utftorunestr(arg, rarg);
num = rarg[0];
} else