Xz: Can you spot the single character that disabled Linux landlock?
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Re: Xz: Can you spot the single character that disabled Linux landlock?
#2Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd...
Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html
xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
Re: Xz: Can you spot the single character that disabled Linux landlock?
#3[deleted]
Re: Xz: Can you spot the single character that disabled Linux landlock?
#4Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd... Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
What does the dot do?
Re: Xz: Can you spot the single character that disabled Linux landlock?
#5Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd... Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
What does the dot do?
The function is “check_c_source_compiles”. The comment indicates that the intention is to confirm that the Landlock functionality can be compiled on the system, in which case it will be enabled.
The stray dot isn’t valid C, so it will never compile. By ensuring it can never compile, Landlock will never be enabled.
Re: Xz: Can you spot the single character that disabled Linux landlock?
#6Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd... Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
What does the dot do?
Fails the build, so that Landlock support is never enabled.
Re: Xz: Can you spot the single character that disabled Linux landlock?
#7Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd... Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
So that function checked if the following C code compiled, and only in that situation enabled the landlock?
Except that lone period, hard to recognize because of its small size and proximity to the left edge of the diff, caused the C code to become always invalid, hence keeping the landlock always disabled?
That's both vilely impressive and impressively vile. I didn't even spot it on my first read-through.
Re: Xz: Can you spot the single character that disabled Linux landlock?
#8[deleted]
Re: Xz: Can you spot the single character that disabled Linux landlock?
#9Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd... Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
So that function checked if the following C code compiled, and only in that situation enabled the landlock? Except that lone period, hard to recognize because of its small size and proximity to the left edge of the diff, caused the C code to become always invalid, hence keeping the landlock always disabled? That's both vilely impressive and impressively vile. I didn't even spot it on my first read-through.
I agree. The way I read this, I missed it completely until I searched for it. I was looking too closely at the rest of the code around defines
Re: Xz: Can you spot the single character that disabled Linux landlock?
#10Answer: https://git.tukaani.org/?p=xz.git;a=commitdiff;h=f9cf4c05edd... Description of Linux's Landlock access control system if you are not familiar with it: https://docs.kernel.org/userspace-api/landlock.html xz official (maybe...) incident response page: https://tukaani.org/xz-backdoor/
So that function checked if the following C code compiled, and only in that situation enabled the landlock? Except that lone period, hard to recognize because of its small size and proximity to the left edge of the diff, caused the C code to become always invalid, hence keeping the landlock always disabled? That's both vilely impressive and impressively vile. I didn't even spot it on my first read-through.
I just got a little more respect for pythonic whitespace-sensitivity
EDIT: come to think of it, even that might not have done much here, where well-formedness is the issue :(