Date: Wed, 2 Aug 2017 19:02:57 -0400 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Subject: Re: possible bug in setjmp implementation for ppc64 On Thu, Aug 03, 2017 at 02:00:03AM +0300, Alexander Monakov wrote: > On Tue, 1 Aug 2017, David Edelsohn wrote: > > "If glibc is built as a static library, the contents of r2 are saved > > in the jmp_buf; but if glibc is built as a dynamic library, the > > contents of the TOC save slot is saved in the jmp_buf. Similarly, if > > glibc is built as a dynamic library, longjmp *updates* the TOC save > > slot with the r2 value from the jmp_buf before returning." > > > > GLIBC setjmp/longjmp code explicitly differs for shared and static > > versions of the library. Musl libc needs equivalent functionality in > > its implementation. > > Note that since Glibc also supports static dlopen, it is possible to arrive > at a situation where libc.a longjmp is used for returning to a call site > of libc.so setjmp, in which case TOC save slot is not restored as it > ought to be, and the caller of setjmp segfaults. A testcase is available at > https://sourceware.org/bugzilla/show_bug.cgi?id=21895 Thanks for investigating and writing this up. Rich
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