From d105de22fc385da878e8db44c9503a7f30419322 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Sun, 29 Jul 2018 19:21:01 -0600 Subject: [PATCH] Fix use-after-free in gdbserver -fsanitize=address pointed out a use-after-free in gdbserver. In particular, handle_detach could reference "process" after it was deleted by detach_inferior. Avoiding this also necessitated changing target_ops::join to take a pid rather than a process_info*. Tested by the buildbot using a few of the gdbserver builders. gdb/gdbserver/ChangeLog 2018-11-29 Tom Tromey * win32-low.c (win32_join): Take pid, not process. * target.h (struct target_ops) : Change argument type. (join_inferior): Change argument name. * spu-low.c (spu_join): Take pid, not process. * server.c (handle_detach): Preserve pid before destroying process. * lynx-low.c (lynx_join): Take pid, not process. * linux-low.c (linux_join): Take pid, not process. --- gdb/gdbserver/ChangeLog | 11 +++++++++++ gdb/gdbserver/linux-low.c | 4 ++-- gdb/gdbserver/lynx-low.c | 2 +- gdb/gdbserver/server.c | 10 +++++++--- gdb/gdbserver/spu-low.c | 4 ++-- gdb/gdbserver/target.h | 8 ++++---- gdb/gdbserver/win32-low.c | 4 ++-- 7 files changed, 29 insertions(+), 14 deletions(-) diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog index 91a62b6228a..ec4d72f81f8 100644 --- a/gdb/gdbserver/ChangeLog +++ b/gdb/gdbserver/ChangeLog @@ -1,3 +1,14 @@ +2018-11-29 Tom Tromey + + * win32-low.c (win32_join): Take pid, not process. + * target.h (struct target_ops) : Change argument type. + (join_inferior): Change argument name. + * spu-low.c (spu_join): Take pid, not process. + * server.c (handle_detach): Preserve pid before destroying + process. + * lynx-low.c (lynx_join): Take pid, not process. + * linux-low.c (linux_join): Take pid, not process. + 2018-11-23 Alan Hayward * linux-aarch64-low.c (aarch64_cannot_store_register): Remove. diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c index 701f3e863c0..4d849279ca3 100644 --- a/gdb/gdbserver/linux-low.c +++ b/gdb/gdbserver/linux-low.c @@ -1670,12 +1670,12 @@ linux_mourn (struct process_info *process) } static void -linux_join (process_info *proc) +linux_join (int pid) { int status, ret; do { - ret = my_waitpid (proc->pid, &status, 0); + ret = my_waitpid (pid, &status, 0); if (WIFEXITED (status) || WIFSIGNALED (status)) break; } while (ret != -1 || errno != ECHILD); diff --git a/gdb/gdbserver/lynx-low.c b/gdb/gdbserver/lynx-low.c index 6c5933bc470..3bf3588a71b 100644 --- a/gdb/gdbserver/lynx-low.c +++ b/gdb/gdbserver/lynx-low.c @@ -562,7 +562,7 @@ lynx_mourn (struct process_info *proc) /* Implement the join target_ops method. */ static void -lynx_join (process_info *proc) +lynx_join (int pid) { /* The PTRACE_DETACH is sufficient to detach from the process. So no need to do anything extra. */ diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c index 4ec3548d644..a0be0d4f7ea 100644 --- a/gdb/gdbserver/server.c +++ b/gdb/gdbserver/server.c @@ -1255,11 +1255,15 @@ handle_detach (char *own_buf) fprintf (stderr, "Detaching from process %d\n", process->pid); stop_tracing (); + + /* We'll need this after PROCESS has been destroyed. */ + int pid = process->pid; + if (detach_inferior (process) != 0) write_enn (own_buf); else { - discard_queued_stop_replies (ptid_t (process->pid)); + discard_queued_stop_replies (ptid_t (pid)); write_ok (own_buf); if (extended_protocol || target_running ()) @@ -1269,7 +1273,7 @@ handle_detach (char *own_buf) and instead treat this like a normal program exit. */ cs.last_status.kind = TARGET_WAITKIND_EXITED; cs.last_status.value.integer = 0; - cs.last_ptid = ptid_t (process->pid); + cs.last_ptid = ptid_t (pid); current_thread = NULL; } @@ -1281,7 +1285,7 @@ handle_detach (char *own_buf) /* If we are attached, then we can exit. Otherwise, we need to hang around doing nothing, until the child is gone. */ - join_inferior (process); + join_inferior (pid); exit (0); } } diff --git a/gdb/gdbserver/spu-low.c b/gdb/gdbserver/spu-low.c index 83a31a203d4..239c2126391 100644 --- a/gdb/gdbserver/spu-low.c +++ b/gdb/gdbserver/spu-low.c @@ -362,12 +362,12 @@ spu_mourn (struct process_info *process) } static void -spu_join (process_info *proc) +spu_join (int pid) { int status, ret; do { - ret = waitpid (proc->pid, &status, 0); + ret = waitpid (pid, &status, 0); if (WIFEXITED (status) || WIFSIGNALED (status)) break; } while (ret != -1 || errno != ECHILD); diff --git a/gdb/gdbserver/target.h b/gdb/gdbserver/target.h index fce54e05adb..6f810b6db9e 100644 --- a/gdb/gdbserver/target.h +++ b/gdb/gdbserver/target.h @@ -103,9 +103,9 @@ struct target_ops void (*mourn) (struct process_info *proc); - /* Wait for process PROC to exit. */ + /* Wait for process PID to exit. */ - void (*join) (process_info *proc); + void (*join) (int pid); /* Return 1 iff the thread with process ID PID is alive. */ @@ -530,8 +530,8 @@ int kill_inferior (process_info *proc); #define store_inferior_registers(regcache, regno) \ (*the_target->store_registers) (regcache, regno) -#define join_inferior(proc) \ - (*the_target->join) (proc) +#define join_inferior(pid) \ + (*the_target->join) (pid) #define target_supports_non_stop() \ (the_target->supports_non_stop ? (*the_target->supports_non_stop ) () : 0) diff --git a/gdb/gdbserver/win32-low.c b/gdb/gdbserver/win32-low.c index 4aed58d3b8e..1ad71c7be99 100644 --- a/gdb/gdbserver/win32-low.c +++ b/gdb/gdbserver/win32-low.c @@ -873,9 +873,9 @@ win32_mourn (struct process_info *process) /* Implementation of target_ops::join. */ static void -win32_join (process_info *proc) +win32_join (int pid) { - HANDLE h = OpenProcess (PROCESS_ALL_ACCESS, FALSE, proc->pid); + HANDLE h = OpenProcess (PROCESS_ALL_ACCESS, FALSE, pid); if (h != NULL) { WaitForSingleObject (h, INFINITE); -- 2.30.2