Hi,
I would like to commit this fix. I tried to avoid the crash in
libcrypto with least possible impact for the DES_fcrypt() API.
ok?
bluhm
On Tue, Dec 05, 2017 at 05:20:49PM +0100, Alexander Bluhm wrote:
> On Fri, Oct 27, 2017 at 01:50:26AM +0200, Jan Engelhardt wrote:
> > #include <openssl/des.h>
> > int main(void) {
> > char salt[3] = {0xf8, 0xd0, 0x00};
> > char out[32];
> > DES_fcrypt("foo", salt, out);
> > }
>
> This program produces a Segmentation fault in OpenBSD current.
>
> > openssl 1.1.x has it fixed (but 1.0.2l does not!) - their commit
> > seems to be 6493e4801e9edbe1ad1e256d4ce9cd55c8aa2242 in
> > https://github.com/openssl/openssl .
>
> Their fix changes the semantics of DES_crypt() and DES_fcrypt().
> They may fail and return NULL now. This was never the case before
> so we may expect that programs do not check it. With DES_fcrypt()
> it is very likely that some uninitilaized content of the return
> string is used.
>
> So I have extended the workaround that was there already. Read the
> comment above the fix. If the salt does not consist of two ascii
> characters, replace it with "AA". This gives a safe result in all
> cases.
>
> ok?
>
> bluhm
>
> Index: lib/libcrypto/des/fcrypt.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/lib/libcrypto/des/fcrypt.c,v
> retrieving revision 1.12
> diff -u -p -r1.12 fcrypt.c
> --- lib/libcrypto/des/fcrypt.c 26 Dec 2016 21:30:10 -0000 1.12
> +++ lib/libcrypto/des/fcrypt.c 5 Dec 2017 16:03:57 -0000
> @@ -78,9 +78,15 @@ char *DES_fcrypt(const char *buf, const
> * crypt to "*". This was found when replacing the crypt in
> * our shared libraries. People found that the disabled
> * accounts effectively had no passwd :-(. */
> - x=ret[0]=((salt[0] == '\0')?'A':salt[0]);
> + x = salt[0];
> + if (x == 0 || x >= sizeof(con_salt))
> + x = 'A';
> + ret[0] = x;
> Eswap0=con_salt[x]<<2;
> - x=ret[1]=((salt[1] == '\0')?'A':salt[1]);
> + x = (salt[0] == '\0') ? 'A' : salt[1];
> + if (x == 0 || x >= sizeof(con_salt))
> + x = 'A';
> + ret[1] = x;
> Eswap1=con_salt[x]<<6;
> /* EAY
> r=strlen(buf);
> Index: regress/lib/libcrypto/des/destest.c
> ===================================================================
> RCS file: /data/mirror/openbsd/cvs/src/regress/lib/libcrypto/des/destest.c,v
> retrieving revision 1.3
> diff -u -p -r1.3 destest.c
> --- regress/lib/libcrypto/des/destest.c 30 Oct 2015 15:58:40 -0000
> 1.3
> +++ regress/lib/libcrypto/des/destest.c 5 Dec 2017 16:02:18 -0000
> @@ -749,18 +749,38 @@ plain[8+4], plain[8+5], plain[8+6], plai
> }
> printf("\n");
> printf("fast crypt test ");
> - str=crypt("testing","ef");
> + str=DES_crypt("testing","ef");
> if (strcmp("efGnQx2725bI2",str) != 0)
> {
> printf("fast crypt error, %s should be efGnQx2725bI2\n",str);
> err=1;
> }
> - str=crypt("bca76;23","yA");
> + str=DES_crypt("bca76;23","yA");
> if (strcmp("yA1Rp/1hZXIJk",str) != 0)
> {
> printf("fast crypt error, %s should be yA1Rp/1hZXIJk\n",str);
> err=1;
> }
> + str = DES_crypt("testing", "\202B");
> + if (strncmp("AB",str,2) != 0) {
> + printf("salt %s first non ascii not replaced with A\n", str);
> + err = 1;
> + }
> + str = DES_crypt("testing", "B\202");
> + if (strncmp("BA",str,2) != 0) {
> + printf("salt %s second non ascii not replaced with A\n", str);
> + err = 1;
> + }
> + str = DES_crypt("testing", "\0B");
> + if (strncmp("AA",str,2) != 0) {
> + printf("salt %s first NUL not replaced with AA\n", str);
> + err = 1;
> + }
> + str = DES_crypt("testing", "B");
> + if (strncmp("BA",str,2) != 0) {
> + printf("salt %s second NUL not replaced with A\n", str);
> + err = 1;
> + }
> printf("\n");
> return(err);
> }
