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Do not cast away const in agent_run_command

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While investigating something else, I noticed some weird code in
agent_run_command (use of memcpy rather than strcpy).  Then I noticed
that 'cmd' is used as both an in and out parameter, despite being
const.

Casting away const like this is bad.  This patch removes the const and
fixes the memcpy.  I also added a static assert to assure myself that
the code in gdbserver is correct -- gdbserver is passing its own
buffer directly to agent_run_command.

Reviewed-By: Andrew Burgess <aburgess@redhat.com>
This commit is contained in:
Tom Tromey 2023-02-14 07:03:11 -07:00
parent 5bed9dc992
commit 81aa19c303
5 changed files with 17 additions and 13 deletions
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7
gdb/linux-nat.c
View file

@ -4114,9 +4114,7 @@ linux_nat_target::static_tracepoint_markers_by_strid (const char *strid)
/* Pause all */
target_stop (ptid);
memcpy (s, "qTfSTM", sizeof ("qTfSTM"));
s[sizeof ("qTfSTM")] = 0;
strcpy (s, "qTfSTM");
agent_run_command (pid, s, strlen (s) + 1);
/* Unpause all. */
@ -4133,8 +4131,7 @@ linux_nat_target::static_tracepoint_markers_by_strid (const char *strid)
}
while (*p++ == ','); /* comma-separated list */
memcpy (s, "qTsSTM", sizeof ("qTsSTM"));
s[sizeof ("qTsSTM")] = 0;
strcpy (s, "qTsSTM");
agent_run_command (pid, s, strlen (s) + 1);
p = s;
}

5
gdbserver/server.cc
View file

@ -51,6 +51,11 @@
#include "gdbsupport/scoped_restore.h"
#include "gdbsupport/search.h"
/* PBUFSIZ must also be at least as big as IPA_CMD_BUF_SIZE, because
the client state data is passed directly to some agent
functions. */
gdb_static_assert (PBUFSIZ >= IPA_CMD_BUF_SIZE);
#define require_running_or_return(BUF) \
if (!target_running ()) \
{ \

2
gdbserver/tracepoint.cc
View file

@ -6820,7 +6820,7 @@ run_inferior_command (char *cmd, int len)
target_pause_all (false);
uninsert_all_breakpoints ();
err = agent_run_command (pid, (const char *) cmd, len);
err = agent_run_command (pid, cmd, len);
reinsert_all_breakpoints ();
target_unpause_all (false);

14
gdbsupport/agent.cc
View file

@ -179,14 +179,16 @@ gdb_connect_sync_socket (int pid)
#endif
}
/* Execute an agent command in the inferior. PID is the value of pid of the
inferior. CMD is the buffer for command. GDB or GDBserver will store the
command into it and fetch the return result from CMD. The interaction
between GDB/GDBserver and the agent is synchronized by a synchronization
socket. Return zero if success, otherwise return non-zero. */
/* Execute an agent command in the inferior. PID is the value of pid
of the inferior. CMD is the buffer for command. It is assumed to
be at least IPA_CMD_BUF_SIZE bytes long. GDB or GDBserver will
store the command into it and fetch the return result from CMD.
The interaction between GDB/GDBserver and the agent is synchronized
by a synchronization socket. Return zero if success, otherwise
return non-zero. */
int
agent_run_command (int pid, const char *cmd, int len)
agent_run_command (int pid, char *cmd, int len)
{
int fd;
int tid = agent_get_helper_thread_id ();

2
gdbsupport/agent.h
View file

@ -22,7 +22,7 @@
#include "gdbsupport/preprocessor.h"
int agent_run_command (int pid, const char *cmd, int len);
int agent_run_command (int pid, char *cmd, int len);
int agent_look_up_symbols (void *);