* [PATCH net] isdn: Partially revert debug format string usage clean up
@ 2015-11-25 6:47 Christoph Biedl
2015-11-25 16:50 ` David Miller
2015-11-25 18:35 ` Kees Cook
0 siblings, 2 replies; 3+ messages in thread
From: Christoph Biedl @ 2015-11-25 6:47 UTC (permalink / raw)
To: netdev, Karsten Keil, Kees Cook
Commit 35a4a57 ("isdn: clean up debug format string usage") introduced
a safeguard to avoid accidential format string interpolation of data
when calling debugl1 or HiSax_putstatus. This did however not take into
account VHiSax_putstatus (called by HiSax_putstatus) does *not* call
vsprintf if the head parameter is NULL - the format string is treated
as plain text then instead. As a result, the string "%s" is processed
literally, and the actual information is lost. This affects the isdnlog
userspace program which stopped logging information since that commit.
So revert the HiSax_putstatus invocations to the previous state.
Fixes: 35a4a5733b0a ("isdn: clean up debug format string usage")
Cc: Kees Cook <keescook@chromium.org>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
---
drivers/isdn/hisax/config.c | 2 +-
drivers/isdn/hisax/hfc_pci.c | 2 +-
drivers/isdn/hisax/hfc_sx.c | 2 +-
drivers/isdn/hisax/q931.c | 6 +++---
4 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/isdn/hisax/config.c b/drivers/isdn/hisax/config.c
index b33f53b..bf04d2a 100644
--- a/drivers/isdn/hisax/config.c
+++ b/drivers/isdn/hisax/config.c
@@ -1896,7 +1896,7 @@ static void EChannel_proc_rcv(struct hisax_d_if *d_if)
ptr--;
*ptr++ = '\n';
*ptr = 0;
- HiSax_putstatus(cs, NULL, "%s", cs->dlog);
+ HiSax_putstatus(cs, NULL, cs->dlog);
} else
HiSax_putstatus(cs, "LogEcho: ",
"warning Frame too big (%d)",
diff --git a/drivers/isdn/hisax/hfc_pci.c b/drivers/isdn/hisax/hfc_pci.c
index 4a48255..90449e1 100644
--- a/drivers/isdn/hisax/hfc_pci.c
+++ b/drivers/isdn/hisax/hfc_pci.c
@@ -901,7 +901,7 @@ Begin:
ptr--;
*ptr++ = '\n';
*ptr = 0;
- HiSax_putstatus(cs, NULL, "%s", cs->dlog);
+ HiSax_putstatus(cs, NULL, cs->dlog);
} else
HiSax_putstatus(cs, "LogEcho: ", "warning Frame too big (%d)", total - 3);
}
diff --git a/drivers/isdn/hisax/hfc_sx.c b/drivers/isdn/hisax/hfc_sx.c
index b1fad81..13b2151 100644
--- a/drivers/isdn/hisax/hfc_sx.c
+++ b/drivers/isdn/hisax/hfc_sx.c
@@ -674,7 +674,7 @@ receive_emsg(struct IsdnCardState *cs)
ptr--;
*ptr++ = '\n';
*ptr = 0;
- HiSax_putstatus(cs, NULL, "%s", cs->dlog);
+ HiSax_putstatus(cs, NULL, cs->dlog);
} else
HiSax_putstatus(cs, "LogEcho: ", "warning Frame too big (%d)", skb->len);
}
diff --git a/drivers/isdn/hisax/q931.c b/drivers/isdn/hisax/q931.c
index b420f8b..ba4beb2 100644
--- a/drivers/isdn/hisax/q931.c
+++ b/drivers/isdn/hisax/q931.c
@@ -1179,7 +1179,7 @@ LogFrame(struct IsdnCardState *cs, u_char *buf, int size)
dp--;
*dp++ = '\n';
*dp = 0;
- HiSax_putstatus(cs, NULL, "%s", cs->dlog);
+ HiSax_putstatus(cs, NULL, cs->dlog);
} else
HiSax_putstatus(cs, "LogFrame: ", "warning Frame too big (%d)", size);
}
@@ -1246,7 +1246,7 @@ dlogframe(struct IsdnCardState *cs, struct sk_buff *skb, int dir)
}
if (finish) {
*dp = 0;
- HiSax_putstatus(cs, NULL, "%s", cs->dlog);
+ HiSax_putstatus(cs, NULL, cs->dlog);
return;
}
if ((0xfe & buf[0]) == PROTO_DIS_N0) { /* 1TR6 */
@@ -1509,5 +1509,5 @@ dlogframe(struct IsdnCardState *cs, struct sk_buff *skb, int dir)
dp += sprintf(dp, "Unknown protocol %x!", buf[0]);
}
*dp = 0;
- HiSax_putstatus(cs, NULL, "%s", cs->dlog);
+ HiSax_putstatus(cs, NULL, cs->dlog);
}
--
2.1.4
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH net] isdn: Partially revert debug format string usage clean up 2015-11-25 6:47 [PATCH net] isdn: Partially revert debug format string usage clean up Christoph Biedl @ 2015-11-25 16:50 ` David Miller 2015-11-25 18:35 ` Kees Cook 1 sibling, 0 replies; 3+ messages in thread From: David Miller @ 2015-11-25 16:50 UTC (permalink / raw) To: linux-kernel.bfrz; +Cc: netdev, isdn, keescook From: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de> Date: Wed, 25 Nov 2015 07:47:40 +0100 > Commit 35a4a57 ("isdn: clean up debug format string usage") introduced > a safeguard to avoid accidential format string interpolation of data > when calling debugl1 or HiSax_putstatus. This did however not take into > account VHiSax_putstatus (called by HiSax_putstatus) does *not* call > vsprintf if the head parameter is NULL - the format string is treated > as plain text then instead. As a result, the string "%s" is processed > literally, and the actual information is lost. This affects the isdnlog > userspace program which stopped logging information since that commit. > > So revert the HiSax_putstatus invocations to the previous state. > > Fixes: 35a4a5733b0a ("isdn: clean up debug format string usage") > Cc: Kees Cook <keescook@chromium.org> > Cc: Karsten Keil <isdn@linux-pingi.de> > Signed-off-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de> Applied, thanks. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH net] isdn: Partially revert debug format string usage clean up 2015-11-25 6:47 [PATCH net] isdn: Partially revert debug format string usage clean up Christoph Biedl 2015-11-25 16:50 ` David Miller @ 2015-11-25 18:35 ` Kees Cook 1 sibling, 0 replies; 3+ messages in thread From: Kees Cook @ 2015-11-25 18:35 UTC (permalink / raw) To: Christoph Biedl; +Cc: Network Development, Karsten Keil On Tue, Nov 24, 2015 at 10:47 PM, Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de> wrote: > Commit 35a4a57 ("isdn: clean up debug format string usage") introduced > a safeguard to avoid accidential format string interpolation of data > when calling debugl1 or HiSax_putstatus. This did however not take into > account VHiSax_putstatus (called by HiSax_putstatus) does *not* call > vsprintf if the head parameter is NULL - the format string is treated > as plain text then instead. As a result, the string "%s" is processed > literally, and the actual information is lost. This affects the isdnlog > userspace program which stopped logging information since that commit. Oh, that's weird, but yeah, these calls aren't expanding format strings, so I'm fine with this change. Acked-by: Kees Cook <keescook@chromium.org> On the other hand, VHiSax_putstatus contains an unchecked data buffer overflow, since it uses tmpbuf without checking lengths at all: p = tmpbuf; if (head) { p += jiftime(p, jiffies); p += sprintf(p, " %s", head); p += vsprintf(p, fmt, args); *p++ = '\n'; *p = 0; len = p - tmpbuf; p = tmpbuf; } else { p = fmt; len = strlen(fmt); } if (len > HISAX_STATUS_BUFSIZE) { spin_unlock_irqrestore(&cs->statlock, flags); printk(KERN_WARNING "HiSax: status overflow %d/%d\n", len, HISAX_STATUS_BUFSIZE); return; } It helpfully detects the overflow, but at this point it's too late: the buffer (and things past it) have already been clobbered. Seems reachable through capi_debug, callc_debug, but nothing jumps out at me as passing taking too-long arguments, though there are some long call chains that touch ioctls and tty stuff, which seems scary. :) Also, though mitigated by needing DEB_DLOG_VERBOSE, there seems to be and overflow in dlogframe too: it doesn't validate against MAX_DLOG_SPACE. For example path: GROUP_TEI CTRL_SAPI ftyp == 3 while ... adds to dp for length of skb ... heap buffer overflow -Kees > > Fixes: 35a4a5733b0a ("isdn: clean up debug format string usage") > Cc: Kees Cook <keescook@chromium.org> > Cc: Karsten Keil <isdn@linux-pingi.de> > Signed-off-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de> > --- > drivers/isdn/hisax/config.c | 2 +- > drivers/isdn/hisax/hfc_pci.c | 2 +- > drivers/isdn/hisax/hfc_sx.c | 2 +- > drivers/isdn/hisax/q931.c | 6 +++--- > 4 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/isdn/hisax/config.c b/drivers/isdn/hisax/config.c > index b33f53b..bf04d2a 100644 > --- a/drivers/isdn/hisax/config.c > +++ b/drivers/isdn/hisax/config.c > @@ -1896,7 +1896,7 @@ static void EChannel_proc_rcv(struct hisax_d_if *d_if) > ptr--; > *ptr++ = '\n'; > *ptr = 0; > - HiSax_putstatus(cs, NULL, "%s", cs->dlog); > + HiSax_putstatus(cs, NULL, cs->dlog); > } else > HiSax_putstatus(cs, "LogEcho: ", > "warning Frame too big (%d)", > diff --git a/drivers/isdn/hisax/hfc_pci.c b/drivers/isdn/hisax/hfc_pci.c > index 4a48255..90449e1 100644 > --- a/drivers/isdn/hisax/hfc_pci.c > +++ b/drivers/isdn/hisax/hfc_pci.c > @@ -901,7 +901,7 @@ Begin: > ptr--; > *ptr++ = '\n'; > *ptr = 0; > - HiSax_putstatus(cs, NULL, "%s", cs->dlog); > + HiSax_putstatus(cs, NULL, cs->dlog); > } else > HiSax_putstatus(cs, "LogEcho: ", "warning Frame too big (%d)", total - 3); > } > diff --git a/drivers/isdn/hisax/hfc_sx.c b/drivers/isdn/hisax/hfc_sx.c > index b1fad81..13b2151 100644 > --- a/drivers/isdn/hisax/hfc_sx.c > +++ b/drivers/isdn/hisax/hfc_sx.c > @@ -674,7 +674,7 @@ receive_emsg(struct IsdnCardState *cs) > ptr--; > *ptr++ = '\n'; > *ptr = 0; > - HiSax_putstatus(cs, NULL, "%s", cs->dlog); > + HiSax_putstatus(cs, NULL, cs->dlog); > } else > HiSax_putstatus(cs, "LogEcho: ", "warning Frame too big (%d)", skb->len); > } > diff --git a/drivers/isdn/hisax/q931.c b/drivers/isdn/hisax/q931.c > index b420f8b..ba4beb2 100644 > --- a/drivers/isdn/hisax/q931.c > +++ b/drivers/isdn/hisax/q931.c > @@ -1179,7 +1179,7 @@ LogFrame(struct IsdnCardState *cs, u_char *buf, int size) > dp--; > *dp++ = '\n'; > *dp = 0; > - HiSax_putstatus(cs, NULL, "%s", cs->dlog); > + HiSax_putstatus(cs, NULL, cs->dlog); > } else > HiSax_putstatus(cs, "LogFrame: ", "warning Frame too big (%d)", size); > } > @@ -1246,7 +1246,7 @@ dlogframe(struct IsdnCardState *cs, struct sk_buff *skb, int dir) > } > if (finish) { > *dp = 0; > - HiSax_putstatus(cs, NULL, "%s", cs->dlog); > + HiSax_putstatus(cs, NULL, cs->dlog); > return; > } > if ((0xfe & buf[0]) == PROTO_DIS_N0) { /* 1TR6 */ > @@ -1509,5 +1509,5 @@ dlogframe(struct IsdnCardState *cs, struct sk_buff *skb, int dir) > dp += sprintf(dp, "Unknown protocol %x!", buf[0]); > } > *dp = 0; > - HiSax_putstatus(cs, NULL, "%s", cs->dlog); > + HiSax_putstatus(cs, NULL, cs->dlog); > } > -- > 2.1.4 > -- Kees Cook Chrome OS & Brillo Security ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-11-25 18:36 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2015-11-25 6:47 [PATCH net] isdn: Partially revert debug format string usage clean up Christoph Biedl 2015-11-25 16:50 ` David Miller 2015-11-25 18:35 ` Kees Cook
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).