The patch titled
uml: fix request->sector update
has been added to the -mm tree. Its filename is
uml-fix-request-sector-update.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: uml: fix request->sector update
From: Jeff Dike <jdike@xxxxxxxxxxx>
It is theoretically possible for a request to finish and be freed between
writing it to the I/O thread and updating the sector count. In this case, the
update will dereference a freed pointer.
To avoid this, I delay the update until processing the next sg segment, when
the request pointer is known to be good.
Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/drivers/ubd_kern.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff -puN arch/um/drivers/ubd_kern.c~uml-fix-request-sector-update arch/um/drivers/ubd_kern.c
--- a/arch/um/drivers/ubd_kern.c~uml-fix-request-sector-update
+++ a/arch/um/drivers/ubd_kern.c
@@ -1082,7 +1082,7 @@ static void do_ubd_request(request_queue
{
struct io_thread_req *io_req;
struct request *req;
- int n;
+ int n, last_sectors;
while(1){
struct ubd *dev = q->queuedata;
@@ -1098,9 +1098,11 @@ static void do_ubd_request(request_queue
}
req = dev->request;
+ last_sectors = 0;
while(dev->start_sg < dev->end_sg){
struct scatterlist *sg = &dev->sg[dev->start_sg];
+ req->sector += last_sectors;
io_req = kmalloc(sizeof(struct io_thread_req),
GFP_ATOMIC);
if(io_req == NULL){
@@ -1112,6 +1114,7 @@ static void do_ubd_request(request_queue
(unsigned long long) req->sector << 9,
sg->offset, sg->length, sg->page);
+ last_sectors = sg->length >> 9;
n = os_write_file(thread_fd, &io_req,
sizeof(struct io_thread_req *));
if(n != sizeof(struct io_thread_req *)){
@@ -1123,7 +1126,6 @@ static void do_ubd_request(request_queue
return;
}
- req->sector += sg->length >> 9;
dev->start_sg++;
}
dev->end_sg = 0;
_
Patches currently in -mm which might be from jdike@xxxxxxxxxxx are
hostfs-convert-to-new-aops.patch
uml-fix-request-sector-update.patch
uml-fix-kernel-stack-size-on-x86_64.patch
-
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