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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
connected.h 
#ifndef CONNECTED_H
#define CONNECTED_H

struct object_id;
struct transport;

/*
 * Take callback data, and return next object name in the buffer.
 * When called after returning the name for the last object, return -1
 * to signal EOF, otherwise return 0.
 */
typedef int (*oid_iterate_fn)(void *, struct object_id *oid);

/*
 * Named-arguments struct for check_connected. All arguments are
 * optional, and can be left to defaults as set by CHECK_CONNECTED_INIT.
 */
struct check_connected_options {
	/* Avoid printing any errors to stderr. */
	int quiet;

	/* --shallow-file to pass to rev-list sub-process */
	const char *shallow_file;

	/* Transport whose objects we are checking, if available. */
	struct transport *transport;

	/*
	 * If non-zero, send error messages to this descriptor rather
	 * than stderr. The descriptor is closed before check_connected
	 * returns.
	 */
	int err_fd;

	/* If non-zero, show progress as we traverse the objects. */
	int progress;

	/*
	 * Insert these variables into the environment of the child process.
	 */
	const char **env;

	/*
	 * If non-zero, check the ancestry chain completely, not stopping at
	 * any existing ref. This is necessary when deepening existing refs
	 * during a fetch.
	 */
	unsigned is_deepening_fetch : 1;
};

#define CHECK_CONNECTED_INIT { 0 }

/*
 * Make sure that all given objects and all objects reachable from them
 * either exist in our object store or (if the repository is a partial
 * clone) are promised to be available.
 *
 * Return 0 if Ok, non zero otherwise (i.e. some missing objects)
 *
 * If "opt" is NULL, behaves as if CHECK_CONNECTED_INIT was passed.
 */
int check_connected(oid_iterate_fn fn, void *cb_data,
		    struct check_connected_options *opt);

#endif /* CONNECTED_H */
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