On 2018-10-02 02:15 AM, Evan Green wrote:
From: Robb Glasser <rglasser@xxxxxxxxxx> sg_ioctl could be spammed by requests, leading to a double free in __free_pages. This protects the entry points of sg_ioctl where the memory could be corrupted by a double call to __free_pages if multiple requests are happening concurrently.
Hi, I don't like this patch. I would like to see the trace for the double call to the __free_pages you are referring too. A test program that show the fault, perhaps? I have test code to "spam" the sg driver and have not seen a double __free_pages that you refer to (see sg3_utils package version 1.44, testing/sg_tst_async.cpp). Currently I am dusting off 20 years of "laparoscopic" patches to the sg driver that have made a bit of a mess of the naming and comments. Also the 16 outstanding requests per file descriptor limit is being removed. Then I want to add the SG_IOSUBMIT and SG_IORECEIVE ioctls proposed by Linus Torvalds two week ago. Executive summary: nak, without further information Doug Gilbert
Signed-off-by: Robb Glasser <rglasser@xxxxxxxxxx> Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Signed-off-by: Evan Green <evgreen@xxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx --- Reposting this patch from last summer, as it looks like it fell in between the cracks. drivers/scsi/sg.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 8a254bb46a9b..25579d8a16b5 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -924,8 +924,10 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg) return -ENXIO; if (!access_ok(VERIFY_WRITE, p, SZ_SG_IO_HDR)) return -EFAULT; + mutex_lock(&sfp->parentdp->open_rel_lock); result = sg_new_write(sfp, filp, p, SZ_SG_IO_HDR, 1, read_only, 1, &srp); + mutex_unlock(&sfp->parentdp->open_rel_lock); if (result < 0) return result; result = wait_event_interruptible(sfp->read_wait,
