From cb31f4195e1e58e57acd9e2de27189879208a426 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 3 Oct 2022 20:26:08 -0400 Subject: fix coredump breakage Let me count the ways in which I'd screwed up: * when emitting a page, handling of gaps in coredump should happen before fetching the current file position. * fix for a problem that occurs on rather uncommon setups (and hadn't been observed in the wild) had been sent very late in the cycle. * ... with badly insufficient testing, introducing an easily reproducible breakage. Without giving it time to soak in -next. Fucked-up-by: Al Viro Reported-by: "J. R. Okajima" Tested-by: "J. R. Okajima" Fixes: 06bbaa6dc53c "[coredump] don't use __kernel_write() on kmap_local_page()" Cc: stable@kernel.org # v6.0-only Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/coredump.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/coredump.c b/fs/coredump.c index 1ab4f5b76a1e..3538f3a63965 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -841,7 +841,7 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) }; struct iov_iter iter; struct file *file = cprm->file; - loff_t pos = file->f_pos; + loff_t pos; ssize_t n; if (cprm->to_skip) { @@ -853,6 +853,7 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) return 0; if (dump_interrupted()) return 0; + pos = file->f_pos; iov_iter_bvec(&iter, WRITE, &bvec, 1, PAGE_SIZE); n = __kernel_write_iter(cprm->file, &iter, &pos); if (n != PAGE_SIZE) -- cgit v1.2.3