[Pkg-zsh-devel] Bug#993843: Bug#993843: zsh-static segfaults immediately

[Axel Beckert]

Control: tag -1 + confirmed
Control: severity serious

Hi David,

David wrote:
> I recently upgraded zsh-static:amd64 from 5.8-6+b2 to 5.8-7.
> 
> With version 5.8-7, /bin/zsh-static segfaults immediately upon
> execution.  The previous 5.8-6+b2 version was fine.

Thanks for the bug report! Can reproduce and confirm it.

Sorry for the trouble. I (and the tests) admittedly only test the
non-static zsh. And except for some special lookups known to be not
possible with static compiled binaries, I also don't expect any
difference in functionality with zsh-static.

A first strace ends as follows:

mprotect(0x7f75ad335000, 4096, PROT_READ) = 0
munmap(0x7f75ad337000, 327870)          = 0
mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f75ad03a000
openat(AT_FDCWD, "/etc/nsswitch.conf", O_RDONLY|O_CLOEXEC) = 11
fstat(11, {st_mode=S_IFREG|0644, st_size=526, ...}) = 0
read(11, "# /etc/nsswitch.conf\n#\n# Example"..., 4096) = 526
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0xe0} ---
+++ killed by SIGSEGV (core dumped) +++

Then again, according to the same strace run, it read
/etc/nsswitch.conf beforehand and didn't segfault there, so it's
likely not that file. Additionally I don't see anything unexpected or
weird in it.

Additionally there are no changes in or new patches against zsh's code
between 5.8-6 and 5.8-7, just packaging changes: Updated packaging
documentation, removal of ancient conflicts and changes how
documentation is distributed over zsh-common and zsh-doc.

So I suspect a change in another package to be the culprit. The big
question is: Which package? Maybe one related to nsswitch.conf.

So far for a first look at this issue...

> A side effect of this is that any user relying on zsh-static as
> their login shell cannot login via ssh any more, since their shell
> immediately crashes.

Of course.

Unfortunately I won't be able to debug this in detail for a few days
due to travelling. But I'll have a closer look into it at the end of
this week.

There's a new upload of zsh planned anyway, although so far due to
less severe (and more long-standing) issues.

		Regards, Axel
-- 
 ,''`.  |  Axel Beckert <abe at debian.org>, https://people.debian.org/~abe/
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