Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=0a6d3a2a3813e7b25267366cfbf9a4a4698dd1c2
Commit: 0a6d3a2a3813e7b25267366cfbf9a4a4698dd1c2
Parent: 7ff9057db7edeb210fd5c00314c52154922d8868
Author: Jeff Dike <[EMAIL PROTECTED]>
AuthorDate: Sun Jul 15 23:38:47 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Jul 16 09:05:38 2007 -0700
uml: fix request->sector update
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 <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
arch/um/drivers/ubd_kern.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 2e09f16..0947f2e 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1083,7 +1083,7 @@ static void do_ubd_request(request_queue_t *q)
{
struct io_thread_req *io_req;
struct request *req;
- int n;
+ int n, last_sectors;
while(1){
struct ubd *dev = q->queuedata;
@@ -1099,9 +1099,11 @@ static void do_ubd_request(request_queue_t *q)
}
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){
@@ -1113,6 +1115,7 @@ static void do_ubd_request(request_queue_t *q)
(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 *)){
@@ -1124,7 +1127,6 @@ static void do_ubd_request(request_queue_t *q)
return;
}
- req->sector += sg->length >> 9;
dev->start_sg++;
}
dev->end_sg = 0;
-
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