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Revision 447ac906e189535e77dcb1f4bbe3f1bc917d4c12 authored by Patrick Steinhardt on 01 December 2022, 14:45:31 UTC, committed by Junio C Hamano on 05 December 2022, 06:14:16 UTC 
attr: fix out-of-bounds read with unreasonable amount of patterns
 
The `struct attr_stack` tracks the stack of all patterns together with
their attributes. When parsing a gitattributes file that has more than
2^31 such patterns though we may trigger multiple out-of-bounds reads on
64 bit platforms. This is because while the `num_matches` variable is an
unsigned integer, we always use a signed integer to iterate over them.

I have not been able to reproduce this issue due to memory constraints
on my systems. But despite the out-of-bounds reads, the worst thing that
can seemingly happen is to call free(3P) with a garbage pointer when
calling `attr_stack_free()`.

Fix this bug by using unsigned integers to iterate over the array. While
this makes the iteration somewhat awkward when iterating in reverse, it
is at least better than knowingly running into an out-of-bounds read.
While at it, convert the call to `ALLOC_GROW` to use `ALLOC_GROW_BY`
instead.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 34ace8b
Raw File
write-or-die.c 
#include "cache.h"
#include "run-command.h"

/*
 * Some cases use stdio, but want to flush after the write
 * to get error handling (and to get better interactive
 * behaviour - not buffering excessively).
 *
 * Of course, if the flush happened within the write itself,
 * we've already lost the error code, and cannot report it any
 * more. So we just ignore that case instead (and hope we get
 * the right error code on the flush).
 *
 * If the file handle is stdout, and stdout is a file, then skip the
 * flush entirely since it's not needed.
 */
void maybe_flush_or_die(FILE *f, const char *desc)
{
	static int skip_stdout_flush = -1;
	struct stat st;
	char *cp;

	if (f == stdout) {
		if (skip_stdout_flush < 0) {
			cp = getenv("GIT_FLUSH");
			if (cp)
				skip_stdout_flush = (atoi(cp) == 0);
			else if ((fstat(fileno(stdout), &st) == 0) &&
				 S_ISREG(st.st_mode))
				skip_stdout_flush = 1;
			else
				skip_stdout_flush = 0;
		}
		if (skip_stdout_flush && !ferror(f))
			return;
	}
	if (fflush(f)) {
		check_pipe(errno);
		die_errno("write failure on '%s'", desc);
	}
}

void fprintf_or_die(FILE *f, const char *fmt, ...)
{
	va_list ap;
	int ret;

	va_start(ap, fmt);
	ret = vfprintf(f, fmt, ap);
	va_end(ap);

	if (ret < 0) {
		check_pipe(errno);
		die_errno("write error");
	}
}

void fsync_or_die(int fd, const char *msg)
{
	if (fsync(fd) < 0) {
		die_errno("fsync error on '%s'", msg);
	}
}

void write_or_die(int fd, const void *buf, size_t count)
{
	if (write_in_full(fd, buf, count) < 0) {
		check_pipe(errno);
		die_errno("write error");
	}
}
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