coredump: let dump_emit() bail out on short writes

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@linux-foundation.org>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-3-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jann Horn 2020-10-15 20:12:43 -07:00 committed by Linus Torvalds
parent 8f942eea12
commit df0c09c011
1 changed files with 11 additions and 11 deletions

View File

@ -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);