Date: Thu, 3 Aug 2017 02:00:03 +0300 (MSK) From: Alexander Monakov <amonakov@...ras.ru> To: musl@...ts.openwall.com Subject: Re: possible bug in setjmp implementation for ppc64 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. Alexander
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