Re: [Bug-wget] wget 1.17 segfaults under openSUSE 13.1 (x86_64; glibc 2.18)

[Tim Rühsen]

Hi,

here is patch to avoid the crash, please review.

@Darshit As you say, we probably should discuss the program logic in
http_loop() regarding if-modified-since !?

Regards, Tim


Am Samstag, 21. November 2015, 00:10:44 schrieb Darshit Shah:
> Another thing that I just remembered, this issue seems to pop up when the
> file being downloaded already exists on disk. Maybe, that is why you're
> seeing the different behaviour?
>
> Try downloading the file when it already exists and see if the problem can
> be reproduced on the newer system.
>
> On 11/20, Darshit Shah wrote:
> >This looks similar to another segfault I've seen. I'm not sure since
> >when it exists in the code, but I did come across one recently. That
> >case was caused when --trust-server-names -N and --content-disposition
> >were all provided to Wget. A wrong logic condition causes Wget to work
> >on output_filename = NULL which eventually resents in a segfault.
> >
> >I'm assuming the case you've provided is very similar to what I've
> >seen. I was using Clang when I saw this issue. Unfortunately, I'm
> >currently swamped with other work and am unable to look more deeply
> >into this.
> >
> >The stack trace provided does match my explanation above, so we should
> >be able to track it down and fix it. Some interplay of multiple
> >options is causing this bug, though I can't explain why it works with
> >one GCC version and not with another. The way I see it, it was a logic
> >bug in the code.
> >
> >Unfortunately, On 11/20, Schleusener, Jens wrote:
> >>Hi,
> >>
> >>under some conditions I get with a self-compiled wget 1.17 binary on
> >>a 64-bit openSUSE 13.1 Linux system a segmentation fault (but the
> >>self-compiled wget 1.16.3 works correctly).
> >>
> >>I could reduce the problem to this usage case:
> >>
> >>wget -N --content-disposition http://ftp.gnu.org/gnu/wget/
> >>
> >>while the usage of only "-N" or "--content-disposition" let wget work.
> >>
> >>Sorry, I am not a C expert but nevertheless I tried to use gdb on
> >>the resulting core dump as best I could with the following result:
> >>
> >>Program terminated with signal SIGSEGV, Segmentation fault.
> >>#0  0x00007f5b0899d42a in strlen () from /lib64/libc.so.6
> >>(gdb) bt
> >>#0  0x00007f5b0899d42a in strlen () from /lib64/libc.so.6
> >>#1  0x0000000000420cdf in set_file_timestamp ()
> >>#2  0x00000000004241e0 in http_loop ()
> >>#3  0x0000000000433619 in retrieve_url ()
> >>#4  0x000000000042c64b in main ()
> >>
> >>The used gcc version is
> >>4.8.1
> >>and a "rpm -qf /lib64/libc.so.6" issues
> >>glibc-2.18-4.38.1.x86_64
> >>
> >>On a newer openSUSE Leap 42.1 Linux system the "identically"
> >>compiled wget doesn't segfault and works ok. On that system the gcc
> >>version is
> >>4.8.5
> >>and a "rpm -qf /lib64/libc.so.6" issues
> >>glibc-2.19-17.4.x86_64
> >>
> >>Regards
> >>
> >>Jens

0001-Fix-SIGSEGV-in-N-content-disposition-combination.patch
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