[PATCH v4 2/5] 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 <torva...@linux-foundation.org>
Signed-off-by: Jann Horn <ja...@google.com>
---
 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