From: Al Viro viro@zeniv.linux.org.uk
commit 4f526fef91b24197d489ff86789744c67f475bb4 upstream.
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 viro@zeniv.linux.org.uk Reported-by: "J. R. Okajima" hooanon05g@gmail.com Tested-by: "J. R. Okajima" hooanon05g@gmail.com Fixes: 06bbaa6dc53c "[coredump] don't use __kernel_write() on kmap_local_page()" Cc: stable@kernel.org # v6.0-only Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/coredump.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/coredump.c +++ b/fs/coredump.c @@ -841,7 +841,7 @@ static int dump_emit_page(struct coredum }; 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 coredum 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)