*** invalid %N$ use detected *** #3944
Comments
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Still fails for me |
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Cant reproduce even with asan. Can u provide more info? Like a backtrace or another reproducer
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ping
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Okay, reproducible only on a PaX-enabled systems |
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uh... why is %n ever being used? On Mon, Jan 11, 2016 at 5:00 PM, Anton Kochkov [email protected]
Jeff Crowell |
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oh nope. not even there.. so its not used at all, maybe its a format string vuln with a specially crafted string. can you show a backtrace? |
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no backtrace is available at that system with this error. |
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Then drop pax :p
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I get this same issue when trying to analyze an 8051 firmware. OS is Arch Linux, kernel 4.4.5-1-ARCH x86_64. Here's the version of radare I'm using (from the Arch Community repo): And the command I'm running: And finally the backtrace: |
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Please update to git and try again
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The issue still exists on master. Non-stripped backtrace: |
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And here's the backtrace with local variables: |
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Apparently, Arch Linux's gcc adds The proper fix is to make diff --git a/global.mk b/global.mk
index 364a61a..a7c48ff 100644
--- a/global.mk
+++ b/global.mk
@@ -34,13 +34,13 @@ WWWROOT=${DATADIR}/radare2/${VERSION}/www
ifneq ($(SILENT),)
@echo LD $<
endif
- $(CC) $(LDFLAGS) -c $(CFLAGS) -o $@ $<
+ $(CC) $(LDFLAGS) -c $(CFLAGS) -U_FORTIFY_SOURCE -o $@ $<
.c.o:
ifneq ($(SILENT),)
@echo "CC $(shell basename $<)"
endif
- $(CC) -c $(CFLAGS) -o $@ $<
+ $(CC) -c $(CFLAGS) -U_FORTIFY_SOURCE -o $@ $<
-include $(TOP)/config-user.mk
-include $(TOP)/mk/platform.mk |
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I don't like the idea of having to disable fortify, but i understand that changing that code is not easy and it will result in a big refactoring because the %$ syntax is hard to be replaced. I dont know which standard itconforms and i wonder if that works on bionic or windows too.. |
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Wikipedia says that %$ is a POSIX thing and not in any version of the C standard. It seems to work fine with fortify disabled so it should work on other operating systems, but of course that increases the risk of input causing buffer overflows. |
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Can you confirm this is still happening in master? |
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@radare well, I have an idea - you won't believe this, but what about using radare2 own *printf implementations - for the standard formats it will fallback to the in-system printf, but it will add support for some very useful extensions. |
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the thing is that i cant find any %N$ in the 8051 code. there’s a %N in the arm disassebler. but it can be fixed. not sure when this was having %N or %$
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@radare still reproduceable on the PaX-enabled Hardened Gentoo. |
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can you point to the file:line?
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Not on this computer - may be will be lucky with the home one. This one has PTRACE disabled. |
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@radare The issue is still happening for me, which isn't surprising since the file the problem statements are in ( You can find the problem lines with this command: grep -rn '%[0-9]\$'Which produces this output: |
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Does itbuilds if u disable that plugin? Can we check if fortity is set from cpp? Maybe we can just avoid building this code in this case
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ping |
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well the issue is there, but the code is not easily refactorizable to get rid of that %N$ thing :(
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Not prioritae, moving to the next milestone. |
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I recently removed all uses of %N$ from the 8051 analyzer. grep suggested by @cyrozap comes up empty. Can someone verify that this issue is resolved? |
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let's close this for now |
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Running on git master: It doesn't crash now, but I do get the following errors: The 8051 is an 8-bit CPU, not a 64-bit one, so I'm not sure where that "bits 64" is coming from or if that's now interfering with anything. Regardless, it seems to work now, so I think we can keep this issue closed. |
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Thanks for fixing this, @astuder! |
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@cyrozap the 64 bit error is because r2 tries to initialize to its defaults (asm.cpu=x86 asm.bits=64) a few times during startup. Not sure how to fix that, but I didn't see any negative impact in practice either so far. |
./run_r2.shfrom https://github.com/XVilka/hacklu/tree/master/demos/Firmware/demo5_it8502e[0x000000]> . ite_it8502.r2pd 5It quits with
*** invalid %N$ use detected ***errorThe text was updated successfully, but these errors were encountered: