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audit: get comm using lock to avoid race in string printing

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When task->comm is passed directly to audit_log_untrustedstring() without
getting a copy or using the task_lock, there is a race that could happen that
would output a NULL (\0) in the output string that would effectively truncate
the rest of the report text after the comm= field in the audit, losing fields.

Use get_task_comm() to get a copy while acquiring the task_lock to prevent
this and to prevent the result from being a mixture of old and new values of
comm.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
This commit is contained in:
Richard Guy Briggs 2014-03-15 18:42:34 -04:00 committed by Eric Paris
parent f874738e8c
commit 9eab339b19
2 changed files with 4 additions and 4 deletions
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5
kernel/audit.c
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@ -1850,7 +1850,7 @@ EXPORT_SYMBOL(audit_log_task_context);
void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk) void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
{ {
const struct cred *cred; const struct cred *cred;
char name[sizeof(tsk->comm)]; char comm[sizeof(tsk->comm)];
struct mm_struct *mm = tsk->mm; struct mm_struct *mm = tsk->mm;
char *tty; char *tty;
@ -1884,9 +1884,8 @@ void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
from_kgid(&init_user_ns, cred->fsgid), from_kgid(&init_user_ns, cred->fsgid),
tty, audit_get_sessionid(tsk)); tty, audit_get_sessionid(tsk));
get_task_comm(name, tsk);
audit_log_format(ab, " comm="); audit_log_format(ab, " comm=");
audit_log_untrustedstring(ab, name); audit_log_untrustedstring(ab, get_task_comm(comm, tsk));
if (mm) { if (mm) {
down_read(&mm->mmap_sem); down_read(&mm->mmap_sem);

3
kernel/auditsc.c
View file

@ -2424,6 +2424,7 @@ static void audit_log_task(struct audit_buffer *ab)
kgid_t gid; kgid_t gid;
unsigned int sessionid; unsigned int sessionid;
struct mm_struct *mm = current->mm; struct mm_struct *mm = current->mm;
char comm[sizeof(current->comm)];
auid = audit_get_loginuid(current); auid = audit_get_loginuid(current);
sessionid = audit_get_sessionid(current); sessionid = audit_get_sessionid(current);
@ -2436,7 +2437,7 @@ static void audit_log_task(struct audit_buffer *ab)
sessionid); sessionid);
audit_log_task_context(ab); audit_log_task_context(ab);
audit_log_format(ab, " pid=%d comm=", task_pid_nr(current)); audit_log_format(ab, " pid=%d comm=", task_pid_nr(current));
audit_log_untrustedstring(ab, current->comm); audit_log_untrustedstring(ab, get_task_comm(comm, current));
if (mm) { if (mm) {
down_read(&mm->mmap_sem); down_read(&mm->mmap_sem);
if (mm->exe_file) if (mm->exe_file)