Fixed race on put_files_struct on exec with proc.
Restoring files on current on error path may lead
to proc having a pointer to already kfree-d files_struct.
Found during OpenVZ stress testing.
Signed-Off-By: Pavel Emelianov <[email protected]>
Signed-Off-By: Kirill Korotaev <[email protected]>
--- ./fs/binfmt_elf.c.fsfix 2006-03-27 14:25:59.000000000 +0400
+++ ./fs/binfmt_elf.c 2006-03-28 13:26:16.000000000 +0400
@@ -1027,8 +1027,13 @@ out_free_file:
sys_close(elf_exec_fileno);
out_free_fh:
if (files) {
- put_files_struct(current->files);
+ struct files_struct *old;
+
+ old = current->files;
+ task_lock(current);
current->files = files;
+ task_unlock(current);
+ put_files_struct(old);
}
out_free_ph:
kfree(elf_phdata);
--- ./fs/binfmt_misc.c.fsfix 2006-03-27 14:25:59.000000000 +0400
+++ ./fs/binfmt_misc.c 2006-03-28 13:27:06.000000000 +0400
@@ -216,8 +216,13 @@ _error:
bprm->interp_data = 0;
_unshare:
if (files) {
- put_files_struct(current->files);
+ struct files_struct *old;
+
+ old = current->files;
+ task_lock(current);
current->files = files;
+ task_unlock(current);
+ put_files_struct(old);
}
goto _ret;
}
--- ./fs/exec.c.fsfix 2006-03-27 14:25:59.000000000 +0400
+++ ./fs/exec.c 2006-03-28 13:28:10.000000000 +0400
@@ -865,7 +865,7 @@ int flush_old_exec(struct linux_binprm *
{
char * name;
int i, ch, retval;
- struct files_struct *files;
+ struct files_struct *files, *old;
char tcomm[sizeof(current->comm)];
/*
@@ -946,8 +946,11 @@ int flush_old_exec(struct linux_binprm *
return 0;
mmap_failed:
- put_files_struct(current->files);
+ old = current->files;
+ task_lock(current);
current->files = files;
+ task_unlock(current);
+ put_files_struct(old);
out:
return retval;
}
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