<ins> Description: patch for CVE-2020-14315 A memory corruption vulnerability is present in bspatch as shipped in Colin Percival’s bsdiff tools version 4.3. Insufficient checks when handling external inputs allows an attacker to bypass the sanity checks in place and write out of a dynamically allocated buffer boundaries. Source: https://svnweb.freebsd.org/base/head/usr.bin/bsdiff/bspatch/bspatch.c?revision=352742&view=co Author: tony mancill <tmancill@debian.org> Comment: The patch was created by comparing the Debian sources to the "Confirmed Patched Version" [1] documented in the X41 D-SEC GmbH Security Advisory: X41-2020-006 [2]. References to FreeBSD capsicum have been dropped.  Definitions for TYPE_MINIMUM and TYPE_MAXIMUM have been borrowed from the Debian coreutils package sources but originate in gnulib [3] and are used to define OFF_MIN and OFF_MAX (limits of off_t). Whitespace changes from the confirmed patched version are also included and keep the difference between the Debian sources and the confirmed patched version minimal. . [1] https://svnweb.freebsd.org/base/head/usr.bin/bsdiff/bspatch/bspatch.c?revision=352742&view=co [2] https://www.openwall.com/lists/oss-security/2020/07/09/2 [3] https://www.gnu.org/software/gnulib/ Last-Update: 2021-04-03 Forwarded: not-needed Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=964796 --- a/bspatch.c +++ b/bspatch.c @@ -1,4 +1,6 @@ /*- + * SPDX-License-Identifier: BSD-2-Clause-FreeBSD + * * Copyright 2003-2005 Colin Percival * All rights reserved * @@ -24,56 +26,148 @@ * POSSIBILITY OF SUCH DAMAGE. */ +#include <sys/cdefs.h> #if 0 -__FBSDID("$FreeBSD: src/usr.bin/bsdiff/bspatch/bspatch.c,v 1.1 2005/08/06 01:59:06 cperciva Exp $"); +__FBSDID("$FreeBSD$"); #endif #include <bzlib.h> -#include <stdlib.h> +#include <err.h> +#include <fcntl.h> +#include <libgen.h> +#include <limits.h> +#include <stdint.h> #include <stdio.h> +#include <stdlib.h> #include <string.h> -#include <err.h> #include <unistd.h> -#include <fcntl.h> + +#ifndef O_BINARY +#define O_BINARY 0 +#endif +#define HEADER_SIZE 32 + +/* TYPE_MINIMUM and TYPE_MAXIMUM taken from coreutils */ +#ifndef TYPE_MINIMUM +#define TYPE_MINIMUM(t)  +  ((t) ((t) 0 < (t) -1 ? (t) 0 : ~ TYPE_MAXIMUM (t))) +#endif +#ifndef TYPE_MAXIMUM +#define TYPE_MAXIMUM(t)  +  ((t) ((t) 0 < (t) -1  +        ? (t) -1  +        : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1))) +#endif + +#ifndef OFF_MAX +#define OFF_MAX TYPE_MAXIMUM(off_t) +#endif + +#ifndef OFF_MIN +#define OFF_MIN TYPE_MINIMUM(off_t) +#endif + +static char *newfile; +static int dirfd = -1; + +static void +exit_cleanup(void) +{ + +	if (dirfd != -1 && newfile != NULL) +		if (unlinkat(dirfd, newfile, 0)) +			warn("unlinkat"); +} + +static inline off_t +add_off_t(off_t a, off_t b) +{ +	off_t result; + +#if __GNUC__ >= 5 +	if (__builtin_add_overflow(a, b, &result)) +		errx(1, "Corrupt patch"); +#else +	if ((b > 0 && a > OFF_MAX - b) || (b < 0 && a < OFF_MIN - b)) +		errx(1, "Corrupt patch"); +	result = a + b; +#endif +	return result; +} static off_t offtin(u_char *buf) { off_t y; -	y=buf[7]&0x7F; -	y=y*256;y+=buf[6]; -	y=y*256;y+=buf[5]; -	y=y*256;y+=buf[4]; -	y=y*256;y+=buf[3]; -	y=y*256;y+=buf[2]; -	y=y*256;y+=buf[1]; -	y=y*256;y+=buf[0]; +	y = buf[7] & 0x7F; +	y = y * 256; y += buf[6]; +	y = y * 256; y += buf[5]; +	y = y * 256; y += buf[4]; +	y = y * 256; y += buf[3]; +	y = y * 256; y += buf[2]; +	y = y * 256; y += buf[1]; +	y = y * 256; y += buf[0]; -	if(buf[7]&0x80) y=-y; +	if (buf[7] & 0x80) +		y = -y; -	return y; +	return (y); } -int main(int argc,char * argv[]) +static void +usage(void) { -	FILE * f, * cpf, * dpf, * epf; -	BZFILE * cpfbz2, * dpfbz2, * epfbz2; + +	fprintf(stderr, "usage: bspatch oldfile newfile patchfilen"); +	exit(1); +} + +int main(int argc, char *argv[]) +{ +	FILE *f, *cpf, *dpf, *epf; +	BZFILE *cpfbz2, *dpfbz2, *epfbz2; +	char *directory, *namebuf; int cbz2err, dbz2err, ebz2err; -	int fd; -	ssize_t oldsize,newsize; -	ssize_t bzctrllen,bzdatalen; -	u_char header[32],buf[8]; +	int newfd, oldfd; +	off_t oldsize, newsize; +	off_t bzctrllen, bzdatalen; +	u_char header[HEADER_SIZE], buf[8]; u_char *old, *new; -	off_t oldpos,newpos; +	off_t oldpos, newpos; off_t ctrl[3]; -	off_t lenread; -	off_t i; +	off_t i, lenread, offset; -	if(argc!=4) errx(1,"usage: %s oldfile newfile patchfilen",argv[0]); +	if (argc != 4) +		usage(); /* Open patch file */ -	if ((f = fopen(argv[3], "r")) == NULL) +	if ((f = fopen(argv[3], "rb")) == NULL) +		err(1, "fopen(%s)", argv[3]); +	/* Open patch file for control block */ +	if ((cpf = fopen(argv[3], "rb")) == NULL) +		err(1, "fopen(%s)", argv[3]); +	/* open patch file for diff block */ +	if ((dpf = fopen(argv[3], "rb")) == NULL) err(1, "fopen(%s)", argv[3]); +	/* open patch file for extra block */ +	if ((epf = fopen(argv[3], "rb")) == NULL) +		err(1, "fopen(%s)", argv[3]); +	/* open oldfile */ +	if ((oldfd = open(argv[1], O_RDONLY | O_BINARY, 0)) < 0) +		err(1, "open(%s)", argv[1]); +	/* open directory where we'll write newfile */ +	if ((namebuf = strdup(argv[2])) == NULL || +	    (directory = dirname(namebuf)) == NULL || +	    (dirfd = open(directory, O_DIRECTORY)) < 0) +		err(1, "open %s", argv[2]); +	free(namebuf); +	if ((newfile = basename(argv[2])) == NULL) +		err(1, "basename"); +	/* open newfile */ +	if ((newfd = openat(dirfd, newfile, +	    O_CREAT | O_TRUNC | O_WRONLY | O_BINARY, 0666)) < 0) +		err(1, "open(%s)", argv[2]); +	atexit(exit_cleanup); /* File format: @@ -90,104 +185,104 @@ */ /* Read header */ -	if (fread(header, 1, 32, f) < 32) { +	if (fread(header, 1, HEADER_SIZE, f) < HEADER_SIZE) { if (feof(f)) -			errx(1, "Corrupt patchn"); +			errx(1, "Corrupt patch"); err(1, "fread(%s)", argv[3]); } /* Check for appropriate magic */ if (memcmp(header, "BSDIFF40", 8) != 0) -		errx(1, "Corrupt patchn"); +		errx(1, "Corrupt patch"); /* Read lengths from header */ -	bzctrllen=offtin(header+8); -	bzdatalen=offtin(header+16); -	newsize=offtin(header+24); -	if((bzctrllen<0) || (bzdatalen<0) || (newsize<0)) -		errx(1,"Corrupt patchn"); +	bzctrllen = offtin(header + 8); +	bzdatalen = offtin(header + 16); +	newsize = offtin(header + 24); +	if (bzctrllen < 0 || bzctrllen > OFF_MAX - HEADER_SIZE || +	    bzdatalen < 0 || bzctrllen + HEADER_SIZE > OFF_MAX - bzdatalen || +	    newsize < 0 || newsize > SSIZE_MAX) +		errx(1, "Corrupt patch"); /* Close patch file and re-open it via libbzip2 at the right places */ if (fclose(f)) err(1, "fclose(%s)", argv[3]); -	if ((cpf = fopen(argv[3], "r")) == NULL) -		err(1, "fopen(%s)", argv[3]); -	if (fseeko(cpf, 32, SEEK_SET)) -		err(1, "fseeko(%s, %lld)", argv[3], -		    (long long)32); +	offset = HEADER_SIZE; +	if (fseeko(cpf, offset, SEEK_SET)) +		err(1, "fseeko(%s, %jd)", argv[3], (intmax_t)offset); if ((cpfbz2 = BZ2_bzReadOpen(&cbz2err, cpf, 0, 0, NULL, 0)) == NULL) errx(1, "BZ2_bzReadOpen, bz2err = %d", cbz2err); -	if ((dpf = fopen(argv[3], "r")) == NULL) -		err(1, "fopen(%s)", argv[3]); -	if (fseeko(dpf, 32 + bzctrllen, SEEK_SET)) -		err(1, "fseeko(%s, %lld)", argv[3], -		    (long long)(32 + bzctrllen)); +	offset = add_off_t(offset, bzctrllen); +	if (fseeko(dpf, offset, SEEK_SET)) +		err(1, "fseeko(%s, %jd)", argv[3], (intmax_t)offset); if ((dpfbz2 = BZ2_bzReadOpen(&dbz2err, dpf, 0, 0, NULL, 0)) == NULL) errx(1, "BZ2_bzReadOpen, bz2err = %d", dbz2err); -	if ((epf = fopen(argv[3], "r")) == NULL) -		err(1, "fopen(%s)", argv[3]); -	if (fseeko(epf, 32 + bzctrllen + bzdatalen, SEEK_SET)) -		err(1, "fseeko(%s, %lld)", argv[3], -		    (long long)(32 + bzctrllen + bzdatalen)); +	offset = add_off_t(offset, bzdatalen); +	if (fseeko(epf, offset, SEEK_SET)) +		err(1, "fseeko(%s, %jd)", argv[3], (intmax_t)offset); if ((epfbz2 = BZ2_bzReadOpen(&ebz2err, epf, 0, 0, NULL, 0)) == NULL) errx(1, "BZ2_bzReadOpen, bz2err = %d", ebz2err); -	if(((fd=open(argv[1],O_RDONLY,0))<0) || -		((oldsize=lseek(fd,0,SEEK_END))==-1) || -		((old=malloc(oldsize+1))==NULL) || -		(lseek(fd,0,SEEK_SET)!=0) || -		(read(fd,old,oldsize)!=oldsize) || -		(close(fd)==-1)) err(1,"%s",argv[1]); -	if((new=malloc(newsize+1))==NULL) err(1,NULL); - -	oldpos=0;newpos=0; -	while(newpos<newsize) { +	if ((oldsize = lseek(oldfd, 0, SEEK_END)) == -1 || +	    oldsize > SSIZE_MAX || +	    (old = malloc(oldsize)) == NULL || +	    lseek(oldfd, 0, SEEK_SET) != 0 || +	    read(oldfd, old, oldsize) != oldsize || +	    close(oldfd) == -1) +		err(1, "%s", argv[1]); +	if ((new = malloc(newsize)) == NULL) +		err(1, NULL); + +	oldpos = 0; +	newpos = 0; +	while (newpos < newsize) { /* Read control data */ -		for(i=0;i<=2;i++) { +		for (i = 0; i <= 2; i++) { lenread = BZ2_bzRead(&cbz2err, cpfbz2, buf, 8); if ((lenread < 8) || ((cbz2err != BZ_OK) && (cbz2err != BZ_STREAM_END))) -				errx(1, "Corrupt patchn"); -			ctrl[i]=offtin(buf); -		}; +				errx(1, "Corrupt patch"); +			ctrl[i] = offtin(buf); +		} /* Sanity-check */ -		if ((ctrl[0] < 0) || (ctrl[1] < 0)) -			errx(1,"Corrupt patchn"); +		if (ctrl[0] < 0 || ctrl[0] > INT_MAX || +		    ctrl[1] < 0 || ctrl[1] > INT_MAX) +			errx(1, "Corrupt patch"); /* Sanity-check */ -		if(newpos+ctrl[0]>newsize) -			errx(1,"Corrupt patchn"); +		if (add_off_t(newpos, ctrl[0]) > newsize) +			errx(1, "Corrupt patch"); /* Read diff string */ lenread = BZ2_bzRead(&dbz2err, dpfbz2, new + newpos, ctrl[0]); if ((lenread < ctrl[0]) || ((dbz2err != BZ_OK) && (dbz2err != BZ_STREAM_END))) -			errx(1, "Corrupt patchn"); +			errx(1, "Corrupt patch"); /* Add old data to diff string */ -		for(i=0;i<ctrl[0];i++) -			if((oldpos+i>=0) && (oldpos+i<oldsize)) -				new[newpos+i]+=old[oldpos+i]; +		for (i = 0; i < ctrl[0]; i++) +			if (add_off_t(oldpos, i) < oldsize) +				new[newpos + i] += old[oldpos + i]; /* Adjust pointers */ -		newpos+=ctrl[0]; -		oldpos+=ctrl[0]; +		newpos = add_off_t(newpos, ctrl[0]); +		oldpos = add_off_t(oldpos, ctrl[0]); /* Sanity-check */ -		if(newpos+ctrl[1]>newsize) -			errx(1,"Corrupt patchn"); +		if (add_off_t(newpos, ctrl[1]) > newsize) +			errx(1, "Corrupt patch"); /* Read extra string */ lenread = BZ2_bzRead(&ebz2err, epfbz2, new + newpos, ctrl[1]); if ((lenread < ctrl[1]) || ((ebz2err != BZ_OK) && (ebz2err != BZ_STREAM_END))) -			errx(1, "Corrupt patchn"); +			errx(1, "Corrupt patch"); /* Adjust pointers */ -		newpos+=ctrl[1]; -		oldpos+=ctrl[2]; -	}; +		newpos = add_off_t(newpos, ctrl[1]); +		oldpos = add_off_t(oldpos, ctrl[2]); +	} /* Clean up the bzip2 reads */ BZ2_bzReadClose(&cbz2err, cpfbz2); @@ -197,12 +292,13 @@ err(1, "fclose(%s)", argv[3]); /* Write the new file */ -	if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,0666))<0) || -		(write(fd,new,newsize)!=newsize) || (close(fd)==-1)) -		err(1,"%s",argv[2]); +	if (write(newfd, new, newsize) != newsize || close(newfd) == -1) +		err(1, "%s", argv[2]); +	/* Disable atexit cleanup */ +	newfile = NULL; free(new); free(old); -	return 0; +	return (0); } </ins>