regset: Prevent null pointer reference on readonly regsets

commit c8e2525 upstream. The regset common infrastructure assumed that regsets would always have .get and .set methods, but not necessarily .active methods. Unfortunately people have since written regsets without .set methods. Rather than putting in stub functions everywhere, handle regsets with null .get or .set methods explicitly. Signed-off-by: H. Peter Anvin <[email protected]> Reviewed-by: Oleg Nesterov <[email protected]> Acked-by: Roland McGrath <[email protected]> Cc: <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
adimgong · Apr 3, 2012 · aad87f0 · aad87f0
1 parent 6f9edd2
commit aad87f0
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
@@ -1452,7 +1452,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t,
 	for (i = 1; i < view->n; ++i) {
 		const struct user_regset *regset = &view->regsets[i];
 		do_thread_regset_writeback(t->task, regset);
-		if (regset->core_note_type &&
+		if (regset->core_note_type && regset->get &&
 		    (!regset->active || regset->active(t->task, regset))) {
 			int ret;
 			size_t size = regset->n * regset->size;

diff --git a/include/linux/regset.h b/include/linux/regset.h
@@ -335,6 +335,9 @@ static inline int copy_regset_to_user(struct task_struct *target,
 {
 	const struct user_regset *regset = &view->regsets[setno];
 
+	if (!regset->get)
+		return -EOPNOTSUPP;
+
 	if (!access_ok(VERIFY_WRITE, data, size))
 		return -EIO;
 
@@ -358,6 +361,9 @@ static inline int copy_regset_from_user(struct task_struct *target,
 {
 	const struct user_regset *regset = &view->regsets[setno];
 
+	if (!regset->set)
+		return -EOPNOTSUPP;
+
 	if (!access_ok(VERIFY_READ, data, size))
 		return -EIO;