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Commit 23aebe16 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

exec: kill bprm->tcomm[], simplify the "basename" logic 



Starting from commit c4ad8f98 ("execve: use 'struct filename *' for
executable name passing") bprm->filename can not go away after
flush_old_exec(), so we do not need to save the binary name in
bprm->tcomm[] added by 96e02d15 ("exec: fix use-after-free bug in
setup_new_exec()").

And there was never need for filename_to_taskname-like code, we can
simply do set_task_comm(kbasename(filename).

This patch has to change set_task_comm() and trace_task_rename() to
accept "const char *", but I think this change is also good.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 32ed74a4

fs/exec.c

+2 −19
Original line number Diff line number Diff line
@@ -1046,7 +1046,7 @@ EXPORT_SYMBOL_GPL(get_task_comm); 
 * so that a new one can be started

 */



void set_task_comm(struct task_struct *tsk, char *buf)

void set_task_comm(struct task_struct *tsk, const char *buf)

{

	task_lock(tsk);

	trace_task_rename(tsk, buf);
@@ -1055,21 +1055,6 @@ void set_task_comm(struct task_struct *tsk, char *buf) 
	perf_event_comm(tsk);

}



static void filename_to_taskname(char *tcomm, const char *fn, unsigned int len)

{

	int i, ch;



	/* Copies the binary name from after last slash */

	for (i = 0; (ch = *(fn++)) != '\0';) {

		if (ch == '/')

			i = 0; /* overwrite what we wrote */

		else

			if (i < len - 1)

				tcomm[i++] = ch;

	}

	tcomm[i] = '\0';

}



int flush_old_exec(struct linux_binprm * bprm)

{

	int retval;
@@ -1083,8 +1068,6 @@ int flush_old_exec(struct linux_binprm * bprm) 
		goto out;



	set_mm_exe_file(bprm->mm, bprm->file);



	filename_to_taskname(bprm->tcomm, bprm->filename, sizeof(bprm->tcomm));

	/*

	 * Release all of the old mmap stuff

	 */
@@ -1127,7 +1110,7 @@ void setup_new_exec(struct linux_binprm * bprm) 
	else

		set_dumpable(current->mm, suid_dumpable);



	set_task_comm(current, bprm->tcomm);

	set_task_comm(current, kbasename(bprm->filename));



	/* Set the new mm task size. We have to do that late because it may

	 * depend on TIF_32BIT which is only updated in flush_thread() on

include/linux/binfmts.h

+0 −1
Original line number Diff line number Diff line
@@ -44,7 +44,6 @@ struct linux_binprm { 
	unsigned interp_flags;

	unsigned interp_data;

	unsigned long loader, exec;

	char tcomm[TASK_COMM_LEN];

};



#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -2357,7 +2357,7 @@ extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, i 
struct task_struct *fork_idle(int);

extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);



extern void set_task_comm(struct task_struct *tsk, char *from);

extern void set_task_comm(struct task_struct *tsk, const char *from);

extern char *get_task_comm(char *to, struct task_struct *tsk);



#ifdef CONFIG_SMP

include/trace/events/task.h

+1 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ TRACE_EVENT(task_newtask, 


TRACE_EVENT(task_rename,



	TP_PROTO(struct task_struct *task, char *comm),

	TP_PROTO(struct task_struct *task, const char *comm),



	TP_ARGS(task, comm),