Date: Tue, 28 May 2013 04:54:17 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r251047 - in head: lib/libc/amd64/gen lib/libc/arm/gen lib/libc/gen lib/libc/i386/gen lib/libc/ia64/gen lib/libc/mips/gen lib/libc/powerpc/gen lib/libc/powerpc64/gen lib/libc/sparc64/ge... Message-ID: <201305280454.r4S4sHHn014272@svn.freebsd.org>
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Author: kib Date: Tue May 28 04:54:16 2013 New Revision: 251047 URL: http://svnweb.freebsd.org/changeset/base/251047 Log: The getcontext() from the __fillcontextx() call in the check_deferred_signal() returns twice, since handle_signal() emulates the return from the normal signal handler by sigreturn(2)ing the passed context. Second return is performed on the destroyed stack frame, because __fillcontextx() has already returned. This causes undefined and bad behaviour, usually the victim thread gets SIGSEGV. Avoid nested frame and the need to return from it by doing direct call to getcontext() in the check_deferred_signal() and using a new private libc helper __fillcontextx2() to complement the context with the extended CPU state if the deferred signal is still present. The __fillcontextx() is now unused, but is kept to allow older libthr.so to be used with the new libc. Mark __fillcontextx() as returning twice [1]. Reported by: pgj Pointy hat to: kib Discussed with: dim Tested by: pgj, dim Suggested by: jilles [1] MFC after: 1 week Modified: head/lib/libc/amd64/gen/getcontextx.c head/lib/libc/arm/gen/getcontextx.c head/lib/libc/gen/Symbol.map head/lib/libc/i386/gen/getcontextx.c head/lib/libc/ia64/gen/getcontextx.c head/lib/libc/mips/gen/getcontextx.c head/lib/libc/powerpc/gen/getcontextx.c head/lib/libc/powerpc64/gen/getcontextx.c head/lib/libc/sparc64/gen/getcontextx.c head/lib/libthr/thread/thr_sig.c head/sys/sys/ucontext.h Modified: head/lib/libc/amd64/gen/getcontextx.c ============================================================================== --- head/lib/libc/amd64/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/amd64/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -57,14 +57,12 @@ __getcontextx_size(void) } int -__fillcontextx(char *ctx) +__fillcontextx2(char *ctx) { struct amd64_get_xfpustate xfpu; ucontext_t *ucp; ucp = (ucontext_t *)ctx; - if (getcontext(ucp) == -1) - return (-1); if (xstate_sz != 0) { xfpu.addr = (char *)(ucp + 1); xfpu.len = xstate_sz; @@ -80,6 +78,18 @@ __fillcontextx(char *ctx) return (0); } +int +__fillcontextx(char *ctx) +{ + ucontext_t *ucp; + + ucp = (ucontext_t *)ctx; + if (getcontext(ucp) == -1) + return (-1); + __fillcontextx2(ctx); + return (0); +} + __weak_reference(__getcontextx, getcontextx); ucontext_t * Modified: head/lib/libc/arm/gen/getcontextx.c ============================================================================== --- head/lib/libc/arm/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/arm/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -40,6 +40,13 @@ __getcontextx_size(void) } int +__fillcontextx2(char *ctx) +{ + + return (0); +} + +int __fillcontextx(char *ctx) { ucontext_t *ucp; Modified: head/lib/libc/gen/Symbol.map ============================================================================== --- head/lib/libc/gen/Symbol.map Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/gen/Symbol.map Tue May 28 04:54:16 2013 (r251047) @@ -529,5 +529,6 @@ FBSDprivate_1.0 { __elf_aux_vector; __pthread_map_stacks_exec; __fillcontextx; + __fillcontextx2; __getcontextx_size; }; Modified: head/lib/libc/i386/gen/getcontextx.c ============================================================================== --- head/lib/libc/i386/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/i386/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -89,14 +89,12 @@ __getcontextx_size(void) } int -__fillcontextx(char *ctx) +__fillcontextx2(char *ctx) { struct i386_get_xfpustate xfpu; ucontext_t *ucp; ucp = (ucontext_t *)ctx; - if (getcontext(ucp) == -1) - return (-1); if (xstate_sz != 0) { xfpu.addr = (char *)(ucp + 1); xfpu.len = xstate_sz; @@ -112,6 +110,18 @@ __fillcontextx(char *ctx) return (0); } +int +__fillcontextx(char *ctx) +{ + ucontext_t *ucp; + + ucp = (ucontext_t *)ctx; + if (getcontext(ucp) == -1) + return (-1); + __fillcontextx2(ctx); + return (0); +} + __weak_reference(__getcontextx, getcontextx); ucontext_t * Modified: head/lib/libc/ia64/gen/getcontextx.c ============================================================================== --- head/lib/libc/ia64/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/ia64/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -40,6 +40,13 @@ __getcontextx_size(void) } int +__fillcontextx2(char *ctx) +{ + + return (0); +} + +int __fillcontextx(char *ctx) { ucontext_t *ucp; Modified: head/lib/libc/mips/gen/getcontextx.c ============================================================================== --- head/lib/libc/mips/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/mips/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -40,6 +40,13 @@ __getcontextx_size(void) } int +__fillcontextx2(char *ctx) +{ + + return (0); +} + +int __fillcontextx(char *ctx) { ucontext_t *ucp; Modified: head/lib/libc/powerpc/gen/getcontextx.c ============================================================================== --- head/lib/libc/powerpc/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/powerpc/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -40,6 +40,13 @@ __getcontextx_size(void) } int +__fillcontextx2(char *ctx) +{ + + return (0); +} + +int __fillcontextx(char *ctx) { ucontext_t *ucp; Modified: head/lib/libc/powerpc64/gen/getcontextx.c ============================================================================== --- head/lib/libc/powerpc64/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/powerpc64/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -40,6 +40,13 @@ __getcontextx_size(void) } int +__fillcontextx2(char *ctx) +{ + + return (0); +} + +int __fillcontextx(char *ctx) { ucontext_t *ucp; Modified: head/lib/libc/sparc64/gen/getcontextx.c ============================================================================== --- head/lib/libc/sparc64/gen/getcontextx.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libc/sparc64/gen/getcontextx.c Tue May 28 04:54:16 2013 (r251047) @@ -40,6 +40,13 @@ __getcontextx_size(void) } int +__fillcontextx2(char *ctx) +{ + + return (0); +} + +int __fillcontextx(char *ctx) { ucontext_t *ucp; Modified: head/lib/libthr/thread/thr_sig.c ============================================================================== --- head/lib/libthr/thread/thr_sig.c Mon May 27 22:45:05 2013 (r251046) +++ head/lib/libthr/thread/thr_sig.c Tue May 28 04:54:16 2013 (r251047) @@ -323,8 +323,13 @@ check_deferred_signal(struct pthread *cu return; #if defined(__amd64__) || defined(__i386__) - uc = alloca(__getcontextx_size()); - __fillcontextx((char *)uc); + int uc_len; + uc_len = __getcontextx_size(); + uc = alloca(uc_len); + getcontext(uc); + if (curthread->deferred_siginfo.si_signo == 0) + return; + __fillcontextx2((char *)uc); #else ucontext_t ucv; uc = &ucv; Modified: head/sys/sys/ucontext.h ============================================================================== --- head/sys/sys/ucontext.h Mon May 27 22:45:05 2013 (r251046) +++ head/sys/sys/ucontext.h Tue May 28 04:54:16 2013 (r251047) @@ -80,7 +80,8 @@ int swapcontext(ucontext_t *, const ucon #if __BSD_VISIBLE int __getcontextx_size(void); -int __fillcontextx(char *ctx); +int __fillcontextx(char *ctx) __returns_twice; +int __fillcontextx2(char *ctx); #endif __END_DECLS
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