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* [musl] Dynamic linker segfault
@ 2022-01-04 21:27 Nihal Jere
  2022-01-04 21:42 ` Rich Felker
  0 siblings, 1 reply; 9+ messages in thread
From: Nihal Jere @ 2022-01-04 21:27 UTC (permalink / raw)
  To: musl

Hi,

ldd from master segfaults when run on [1] and [2]. It happens on
this[3] line. It seems to happen due to the intersection of a few
factors:

1. The segment at the lowest address is read-only.
2. A segment on the the same page is read/write.
3. The read/write segment has memsz > filesz.

This results in a segfault, as it tries to memset[3] on the mmap
created here[4], which has the same protection as the segment at
the lowest address (i.e. read-only).

As far as I can see, the options are to either:

a. detect this and throw an error.
b. 'or' together the protection flags of all the segments on the page.

I'm not sure what the right behavior is, but I don't think segfaulting
is right, and I'm sure there are people here what's correct.

Best,
Nihal

[1] https://github.com/golang/go/blob/master/src/debug/elf/testdata/go-relocation-test-gcc930-ranges-no-rela-x86-64
[2] https://github.com/golang/go/blob/master/src/debug/elf/testdata/go-relocation-test-gcc930-ranges-with-rela-x86-64
[3] https://git.musl-libc.org/cgit/musl/tree/ldso/dynlink.c#n783
[4] https://git.musl-libc.org/cgit/musl/tree/ldso/dynlink.c#n742

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2022-01-10 13:30 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-01-04 21:27 [musl] Dynamic linker segfault Nihal Jere
2022-01-04 21:42 ` Rich Felker
2022-01-05  8:56   ` Florian Weimer
2022-01-05 13:49     ` Rich Felker
2022-01-05 14:00       ` Florian Weimer
2022-01-05 15:00         ` Rich Felker
2022-01-07 13:58           ` Florian Weimer
2022-01-07 17:35             ` Rich Felker
2022-01-10 13:30               ` Florian Weimer

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