diff options
Diffstat (limited to 'libsandbox')
| -rw-r--r-- | libsandbox/trace.c | 28 |
1 files changed, 14 insertions, 14 deletions
diff --git a/libsandbox/trace.c b/libsandbox/trace.c index 47d2bdf..99ef8cd 100644 --- a/libsandbox/trace.c +++ b/libsandbox/trace.c @@ -93,10 +93,14 @@ static char *do_peekstr(unsigned long lptr) #ifdef HAVE_PROCESS_VM_READV struct iovec liov, riov; - /* We can't cross remote page boundaries when using this :( */ + /* We can't cross remote page boundaries when using this :(. + * The first call reads up to the edge of the page boundary since we + * have no (easy) way of knowing if the next page is valid. This is + * less effort than reading in the /proc/.../maps file and walking it. + */ l = 0x1000; riov.iov_base = (void *)lptr; - len = lptr % l; + len = l - (lptr % l); if (!len) len = l; liov.iov_base = ret = xmalloc(len); @@ -105,27 +109,23 @@ static char *do_peekstr(unsigned long lptr) while (1) { if (process_vm_readv(trace_pid, &liov, 1, &riov, 1, 0) == -1) { int e = errno; - if (e == ENOSYS) + if (e == ENOSYS) { + /* This can happen if run on older kernels but built with newer ones. */ + break; + } else if (e == EFAULT) { + /* This can happen if the target process uses a bad pointer. #560396 */ break; - sb_eqawarn("process_vm_readv(%i, %p{%p, %zu}, 1, %p{%p, %zu}, 1, 0) failed: %s\n", + } + sb_ebort("ISE:do_peekstr:process_vm_readv(%i, %p{%p, %#zx}, 1, %p{%p, %#zx}, 1, 0) failed: %s\n", trace_pid, &liov, liov.iov_base, liov.iov_len, &riov, riov.iov_base, riov.iov_len, strerror(e)); - if (e == EFAULT) { - /* This sometimes happens, but it's not clear why. - * Throw some extended debugging info before falling - * back to the ptrace code. #560396 - */ - break; - } - sb_ebort("ISE:do_peekstr: process_vm_readv() hates us: %s\n", - strerror(e)); } if (memchr(liov.iov_base, '\0', liov.iov_len) != NULL) return ret; - riov.iov_base += l; + riov.iov_base += riov.iov_len; riov.iov_len = liov.iov_len = l; len += l; ret = xrealloc(ret, len); |