[PATCH v5 2/7] coredump: Let dump_emit() bail out on short writes

[Jann Horn]

dump_emit() has a retry loop, but there seems to be no way for that retry
logic to actually be used; and it was also buggy, writing the same data
repeatedly after a short write.

Let's just bail out on a short write.

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
---
 fs/coredump.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index 76e7c10edfc0..5e24c06092c9 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -840,17 +840,17 @@ int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
 	ssize_t n;
 	if (cprm->written + nr > cprm->limit)
 		return 0;
-	while (nr) {
-		if (dump_interrupted())
-			return 0;
-		n = __kernel_write(file, addr, nr, &pos);
-		if (n <= 0)
-			return 0;
-		file->f_pos = pos;
-		cprm->written += n;
-		cprm->pos += n;
-		nr -= n;
-	}
+
+
+	if (dump_interrupted())
+		return 0;
+	n = __kernel_write(file, addr, nr, &pos);
+	if (n != nr)
+		return 0;
+	file->f_pos = pos;
+	cprm->written += n;
+	cprm->pos += n;
+
 	return 1;
 }
 EXPORT_SYMBOL(dump_emit);
-- 
2.28.0.297.g1956fa8f8d-goog