From: Jann Horn <jannh@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@lst.de>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Eric W . Biederman" <ebiederm@xmission.com>,
Oleg Nesterov <oleg@redhat.com>
Subject: [PATCH v3 2/5] coredump: Let dump_emit() bail out on short writes
Date: Tue, 18 Aug 2020 08:12:36 +0200 [thread overview]
Message-ID: <20200818061239.29091-3-jannh@google.com> (raw)
In-Reply-To: <20200818061239.29091-1-jannh@google.com>
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>
---
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);
--
2.28.0.220.ged08abb693-goog
next prev parent reply other threads:[~2020-08-18 6:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-18 6:12 [PATCH v3 0/5] Fix ELF / FDPIC ELF core dumping, and use mmap_lock properly in there Jann Horn
2020-08-18 6:12 ` [PATCH v3 1/5] binfmt_elf_fdpic: Stop using dump_emit() on user pointers on !MMU Jann Horn
2020-08-18 6:12 ` Jann Horn [this message]
2020-08-18 13:40 ` [PATCH v3 2/5] coredump: Let dump_emit() bail out on short writes Oleg Nesterov
2020-08-18 15:08 ` Jann Horn
2020-08-18 15:17 ` Al Viro
2020-08-18 6:12 ` [PATCH v3 3/5] coredump: Refactor page range dumping into common helper Jann Horn
2020-08-18 6:12 ` [PATCH v3 4/5] binfmt_elf, binfmt_elf_fdpic: Use a VMA list snapshot Jann Horn
2020-08-18 8:18 ` Linus Torvalds
2020-08-18 8:31 ` Jann Horn
2020-08-18 6:12 ` [PATCH v3 5/5] mm/gup: Take mmap_lock in get_dump_page() Jann Horn
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