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Revision b3118bdc91876cbc04b7e81dcf7bea71d86ce4f8 authored by Shawn O. Pearce on 14 October 2009, 14:23:51 UTC, committed by Junio C Hamano on 14 October 2009, 20:39:37 UTC 
sha1_file: Fix infinite loop when pack is corrupted
 
Some types of corruption to a pack may confuse the deflate stream
which stores an object.  In Andy's reported case a 36 byte region
of the pack was overwritten, leading to what appeared to be a valid
deflate stream that was trying to produce a result larger than our
allocated output buffer could accept.

Z_BUF_ERROR is returned from inflate() if either the input buffer
needs more input bytes, or the output buffer has run out of space.
Previously we only considered the former case, as it meant we needed
to move the stream's input buffer to the next window in the pack.

We now abort the loop if inflate() returns Z_BUF_ERROR without
consuming the entire input buffer it was given, or has filled
the entire output buffer but has not yet returned Z_STREAM_END.
Either state is a clear indicator that this loop is not working
as expected, and should not continue.

This problem cannot occur with loose objects as we open the entire
loose object as a single buffer and treat Z_BUF_ERROR as an error.

Reported-by: Andy Isaacson <adi@hexapodia.org>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 583371a
Raw File
tree-walk.h 
#ifndef TREE_WALK_H
#define TREE_WALK_H

struct name_entry {
	const unsigned char *sha1;
	const char *path;
	unsigned int mode;
};

struct tree_desc {
	const void *buffer;
	struct name_entry entry;
	unsigned int size;
};

static inline const unsigned char *tree_entry_extract(struct tree_desc *desc, const char **pathp, unsigned int *modep)
{
	*pathp = desc->entry.path;
	*modep = canon_mode(desc->entry.mode);
	return desc->entry.sha1;
}

static inline int tree_entry_len(const char *name, const unsigned char *sha1)
{
	return (const char *)sha1 - name - 1;
}

void update_tree_entry(struct tree_desc *);
void init_tree_desc(struct tree_desc *desc, const void *buf, unsigned long size);

/* Helper function that does both of the above and returns true for success */
int tree_entry(struct tree_desc *, struct name_entry *);

void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1);

struct traverse_info;
typedef int (*traverse_callback_t)(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *);
int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info);

struct traverse_info {
	struct traverse_info *prev;
	struct name_entry name;
	int pathlen;

	unsigned long conflicts;
	traverse_callback_t fn;
	void *data;
};

int get_tree_entry(const unsigned char *, const char *, unsigned char *, unsigned *);
extern char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n);
extern void setup_traverse_info(struct traverse_info *info, const char *base);

static inline int traverse_path_len(const struct traverse_info *info, const struct name_entry *n)
{
	return info->pathlen + tree_entry_len(n->path, n->sha1);
}

#endif
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