* Bruno Haible: > So, in the normal cases (link with '-lpthread', link without '-lpthread', > and even with dlopen()), everything will work fine. The only problematic > case thus is the the use of LD_PRELOAD. Right?
LD_PRELOAD and glibc 2.34 as originally planned. > I think few packages in a distro will be affected. And few users are > using LD_PRELOAD on their own, because since the time when glibc > started to use 'internal' calls to system calls where possible, there > are not a lot of uses of LD_PRELOAD that still work. We get the occasional bug report when these things break. We have not seen much of that yet because our gnulib-using programs are still at older versions for most of our users. Here's an example of such a bug report, although not for libpthread: powerpc: libc segfaults when LD_PRELOADed with libgcc <https://sourceware.org/bugzilla/show_bug.cgi?id=26615> I think in this bug, libc.so.6 was invoked during some build process (which could easily run bison as well, so it has to work with LD_PRELOAD). >> No. glibc 2.34 will behave as if an implicit -lpthread is present on >> the linker program line. > > Good. This means a bullet-proof way for a distro to avoid the problem > is to "rebuild the world" after importing glibc 2.34. Yeah, but that's not good enough. So I spent today on coming up with a workaround in glibc. >> No, it's unrelated. The crash or other undefined behavior is a >> consequence of actions of the link editor and cannot be reverted at run >> time. > > In other words, the problem is that > - there are some/many binaries out there, that were produced by an 'ld' > that did not anticipate the changes in glibc 2.34, and > - these binaries have a problem not when run directly, but only when > run with LD_PRELOAD. > > Right? No, glibc 2.34 won't need LD_PRELOAD to expose the bug. LD_PRELOAD is just a development aid that reveals the problem with glibc 2.33 and earlier. Thanks, Florian