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

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Starting from commit c4ad8f98be ("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 96e02d1586 ("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: Oleg Nesterov <oleg@redhat.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-04-07 15:38:39 -07:00 • committed by Linus Torvalds
parent 32ed74a4b9
commit 23aebe1691
4 changed files with 4 additions and 22 deletions
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21
fs/exec.c
View file

@ -1046,7 +1046,7 @@ EXPORT_SYMBOL_GPL(get_task_comm);
* so that a new one can be started * 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); task_lock(tsk);
trace_task_rename(tsk, buf); trace_task_rename(tsk, buf);
@ -1055,21 +1055,6 @@ void set_task_comm(struct task_struct *tsk, char *buf)
perf_event_comm(tsk); 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 flush_old_exec(struct linux_binprm * bprm)
{ {
int retval; int retval;
@ -1083,8 +1068,6 @@ int flush_old_exec(struct linux_binprm * bprm)
goto out; goto out;
set_mm_exe_file(bprm->mm, bprm->file); 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 * Release all of the old mmap stuff
*/ */
@ -1127,7 +1110,7 @@ void setup_new_exec(struct linux_binprm * bprm)
else else
set_dumpable(current->mm, suid_dumpable); 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 /* 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 * depend on TIF_32BIT which is only updated in flush_thread() on

1
include/linux/binfmts.h
View file

@ -44,7 +44,6 @@ struct linux_binprm {
unsigned interp_flags; unsigned interp_flags;
unsigned interp_data; unsigned interp_data;
unsigned long loader, exec; unsigned long loader, exec;
char tcomm[TASK_COMM_LEN];
}; };
#define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0 #define BINPRM_FLAGS_ENFORCE_NONDUMP_BIT 0

2
include/linux/sched.h
View file

@ -2357,7 +2357,7 @@ extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, i
struct task_struct *fork_idle(int); struct task_struct *fork_idle(int);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags); 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); extern char *get_task_comm(char *to, struct task_struct *tsk);
#ifdef CONFIG_SMP #ifdef CONFIG_SMP

2
include/trace/events/task.h
View file

@ -32,7 +32,7 @@ TRACE_EVENT(task_newtask,
TRACE_EVENT(task_rename, 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), TP_ARGS(task, comm),