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authorChristopher Yeoh <cyeoh@au1.ibm.com>2012-02-02 11:34:09 +1030
committerLinus Torvalds <torvalds@linux-foundation.org>2012-02-02 12:55:17 -0800
commit8cdb878dcb359fd1137e9abdee9322f5e9bcfdf8 (patch)
tree146afc01f3c1d7cbc944328484d077032bc53bfd /mm
parent24b36da33c64368775f4ef9386d44dce1d2bc8cf (diff)
downloadlinux-8cdb878dcb359fd1137e9abdee9322f5e9bcfdf8.tar.gz
Fix race in process_vm_rw_core
This fixes the race in process_vm_core found by Oleg (see http://article.gmane.org/gmane.linux.kernel/1235667/ for details). This has been updated since I last sent it as the creation of the new mm_access() function did almost exactly the same thing as parts of the previous version of this patch did. In order to use mm_access() even when /proc isn't enabled, we move it to kernel/fork.c where other related process mm access functions already are. Signed-off-by: Chris Yeoh <yeohc@au1.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/process_vm_access.c23
1 files changed, 9 insertions, 14 deletions
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index e920aa3ce10..c20ff48994c 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -298,23 +298,18 @@ static ssize_t process_vm_rw_core(pid_t pid, const struct iovec *lvec,
goto free_proc_pages;
}
- task_lock(task);
- if (__ptrace_may_access(task, PTRACE_MODE_ATTACH)) {
- task_unlock(task);
- rc = -EPERM;
- goto put_task_struct;
- }
- mm = task->mm;
-
- if (!mm || (task->flags & PF_KTHREAD)) {
- task_unlock(task);
- rc = -EINVAL;
+ mm = mm_access(task, PTRACE_MODE_ATTACH);
+ if (!mm || IS_ERR(mm)) {
+ rc = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
+ /*
+ * Explicitly map EACCES to EPERM as EPERM is a more a
+ * appropriate error code for process_vw_readv/writev
+ */
+ if (rc == -EACCES)
+ rc = -EPERM;
goto put_task_struct;
}
- atomic_inc(&mm->mm_users);
- task_unlock(task);
-
for (i = 0; i < riovcnt && iov_l_curr_idx < liovcnt; i++) {
rc = process_vm_rw_single_vec(
(unsigned long)rvec[i].iov_base, rvec[i].iov_len,