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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
gpg-interface.h 
#ifndef GPG_INTERFACE_H
#define GPG_INTERFACE_H

struct strbuf;

#define GPG_VERIFY_VERBOSE		1
#define GPG_VERIFY_RAW			2
#define GPG_VERIFY_OMIT_STATUS	4

enum signature_trust_level {
	TRUST_UNDEFINED,
	TRUST_NEVER,
	TRUST_MARGINAL,
	TRUST_FULLY,
	TRUST_ULTIMATE,
};

struct signature_check {
	char *payload;
	char *gpg_output;
	char *gpg_status;

	/*
	 * possible "result":
	 * 0 (not checked)
	 * N (checked but no further result)
	 * G (good)
	 * B (bad)
	 */
	char result;
	char *signer;
	char *key;
	char *fingerprint;
	char *primary_key_fingerprint;
	enum signature_trust_level trust_level;
};

void signature_check_clear(struct signature_check *sigc);

/*
 * Look at GPG signed content (e.g. a signed tag object), whose
 * payload is followed by a detached signature on it.  Return the
 * offset where the embedded detached signature begins, or the end of
 * the data when there is no such signature.
 */
size_t parse_signature(const char *buf, size_t size);

/*
 * Create a detached signature for the contents of "buffer" and append
 * it after "signature"; "buffer" and "signature" can be the same
 * strbuf instance, which would cause the detached signature appended
 * at the end.
 */
int sign_buffer(struct strbuf *buffer, struct strbuf *signature,
		const char *signing_key);

int git_gpg_config(const char *, const char *, void *);
void set_signing_key(const char *);
const char *get_signing_key(void);
int check_signature(const char *payload, size_t plen,
		    const char *signature, size_t slen,
		    struct signature_check *sigc);
void print_signature_buffer(const struct signature_check *sigc,
			    unsigned flags);

#endif
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