[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] question about SIGSEGV in datacopier_readable in libxl_aoutil.c
Hi, List, I'm trying to add migration APIs to libvirt libxl driver. In testing HVM migration, on source side, when executing libxl_domain_suspend, often meet SIGSEGV in libxl_aoutil.c: datacopier_readable, the malloc() function place:ÂÂÂÂÂ if (!buf || buf->used >= sizeof(buf->buf)) { ÂÂÂÂÂÂÂÂÂÂÂ buf = malloc(sizeof(*buf)); #valgrind --leak-check=full /usr/sbin/libvirtd -l -d [snip] ==7510== Syscall param read(buf) points to unaddressable byte(s) ==7510==ÂÂÂ at 0x8ECC76D: ??? (syscall-template.S:82) ==7510==ÂÂÂ by 0x14AB3070: datacopier_readable (unistd.h:45) ==7510==ÂÂÂ by 0x14AB833C: afterpoll_internal (libxl_event.c:995) ==7510==ÂÂÂ by 0x14AB8F16: eventloop_iteration (libxl_event.c:1440) ==7510==ÂÂÂ by 0x14AB9439: libxl__ao_inprogress (libxl_event.c:1685) ==7510==ÂÂÂ by 0x14A9ABF7: libxl_domain_suspend (libxl.c:785) ==7510==ÂÂÂ by 0x148404B3: libxlDomainMigratePerform3 (libxl_driver.c:5100) ==7510==ÂÂÂ by 0x5390CFA: virDomainMigratePerform3 (libvirt.c:7050) ==7510==ÂÂÂ by 0x12C262: remoteDispatchDomainMigratePerform3Helper (remote.c:3507) ==7510==ÂÂÂ by 0x53EACBE: virNetServerProgramDispatch (virnetserverprogram.c:435) ==7510==ÂÂÂ by 0x53EBCBD: virNetServerProcessMsg (virnetserver.c:165) ==7510==ÂÂÂ by 0x53EC912: virNetServerHandleJob (virnetserver.c:186) ==7510==Â Address 0x18a409ec is 0 bytes after a block of size 28 alloc'd ==7510==ÂÂÂ at 0x4C26FFB: calloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) ==7510==ÂÂÂ by 0x14AAECB6: libxl__zalloc (libxl_internal.c:83) ==7510==ÂÂÂ by 0x14AB33B0: libxl__datacopier_prefixdata (libxl_aoutils.c:92) ==7510==ÂÂÂ by 0x14AA6CDC: libxl__domain_save_device_model (libxl_dom.c:1447) ==7510==ÂÂÂ by 0x14AA8097: libxl__xc_domain_save_done (libxl_dom.c:1382) ==7510==ÂÂÂ by 0x14AB4268: helper_done (libxl_save_callout.c:332) ==7510==ÂÂÂ by 0x14AB4CA2: helper_exited (libxl_save_callout.c:317) ==7510==ÂÂÂ by 0x14ABB274: childproc_reaped (libxl_fork.c:264) ==7510==ÂÂÂ by 0x14ABB97A: libxl__fork_selfpipe_woken (libxl_fork.c:300) ==7510==ÂÂÂ by 0x14AB83A0: afterpoll_internal (libxl_event.c:1008) ==7510==ÂÂÂ by 0x14AB8F16: eventloop_iteration (libxl_event.c:1440) ==7510==ÂÂÂ by 0x14AB9439: libxl__ao_inprogress (libxl_event.c:1685) ==7510== --7510-- VALGRIND INTERNAL ERROR: Valgrind received a signal 11 (SIGSEGV) - exiting --7510-- si_code=80;Â Faulting address: 0x0;Â sp: 0x406ad5da0 I couldn't find a clear problem in the code, but after trying to change the code a little, it turned to be working. Following is the change. --- a/tools/libxl/libxl_aoutils.c +++ b/tools/libxl/libxl_aoutils.c @@ -89,7 +89,8 @@ void libxl__datacopier_prefixdata(libxl_ ÂÂÂÂ assert(len < dc->maxsz - dc->used); -ÂÂÂ buf = libxl__zalloc(NOGC, sizeof(*buf) - sizeof(buf->buf) + len); +//ÂÂÂ buf = libxl__zalloc(NOGC, sizeof(*buf) - sizeof(buf->buf) + len); +ÂÂÂ buf = libxl__zalloc(NOGC, sizeof(libxl__datacopier_buf)); ÂÂÂÂ buf->used = len; ÂÂÂÂ memcpy(buf->buf, data, len); @@ -141,10 +142,11 @@ static void datacopier_readable(libxl__e ÂÂÂÂÂÂÂÂ libxl__datacopier_buf *buf = ÂÂÂÂÂÂÂÂÂÂÂÂ LIBXL_TAILQ_LAST(&dc->bufs, libxl__datacopier_bufs); ÂÂÂÂÂÂÂÂ if (!buf || buf->used >= sizeof(buf->buf)) { -ÂÂÂÂÂÂÂÂÂÂÂ buf = malloc(sizeof(*buf)); -ÂÂÂÂÂÂÂÂÂÂÂ if (!buf) libxl__alloc_failed(CTX, __func__, 1, sizeof(*buf)); -ÂÂÂÂÂÂÂÂÂÂÂ buf->used = 0; -ÂÂÂÂÂÂÂÂÂÂÂ LIBXL_TAILQ_INSERT_TAIL(&dc->bufs, buf, entry); +ÂÂÂÂÂÂÂÂÂÂÂ libxl__datacopier_buf *newbuf = malloc(sizeof(libxl__datacopier_buf)); +ÂÂÂÂÂÂÂÂÂÂÂ if (!newbuf) libxl__alloc_failed(CTX, __func__, 1, sizeof(libxl__datacopier_buf)); +ÂÂÂÂÂÂÂÂÂÂÂ newbuf->used = 0; +ÂÂÂÂÂÂÂÂÂÂÂ LIBXL_TAILQ_INSERT_TAIL(&dc->bufs, newbuf, entry); +ÂÂÂÂÂÂÂÂÂÂÂ buf = newbuf; ÂÂÂÂÂÂÂÂ } ÂÂÂÂÂÂÂÂ int r = read(ev->fd, ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ buf->buf + buf->used, Could anybody familiar with this part of code take a look at it? Thanks, Chunyan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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