This is a note to let you know that I've just added the patch titled kernel/resource.c: fix muxed resource handling in __request_region() to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kernel-resource.c-fix-muxed-resource-handling-in-__request_region.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 59ceeaaf355fa0fb16558ef7c24413c804932ada Mon Sep 17 00:00:00 2001 From: Simon Guinot <simon.guinot@xxxxxxxxxxxx> Date: Thu, 10 Sep 2015 00:15:18 +0200 Subject: kernel/resource.c: fix muxed resource handling in __request_region() From: Simon Guinot <simon.guinot@xxxxxxxxxxxx> commit 59ceeaaf355fa0fb16558ef7c24413c804932ada upstream. In __request_region, if a conflict with a BUSY and MUXED resource is detected, then the caller goes to sleep and waits for the resource to be released. A pointer on the conflicting resource is kept. At wake-up this pointer is used as a parent to retry to request the region. A first problem is that this pointer might well be invalid (if for example the conflicting resource have already been freed). Another problem is that the next call to __request_region() fails to detect a remaining conflict. The previously conflicting resource is passed as a parameter and __request_region() will look for a conflict among the children of this resource and not at the resource itself. It is likely to succeed anyway, even if there is still a conflict. Instead, the parent of the conflicting resource should be passed to __request_region(). As a fix, this patch doesn't update the parent resource pointer in the case we have to wait for a muxed region right after. Reported-and-tested-by: Vincent Pelletier <plr.vincent@xxxxxxxxx> Signed-off-by: Simon Guinot <simon.guinot@xxxxxxxxxxxx> Tested-by: Vincent Donnefort <vdonnefort@xxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/resource.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/kernel/resource.c +++ b/kernel/resource.c @@ -1083,9 +1083,10 @@ struct resource * __request_region(struc if (!conflict) break; if (conflict != parent) { - parent = conflict; - if (!(conflict->flags & IORESOURCE_BUSY)) + if (!(conflict->flags & IORESOURCE_BUSY)) { + parent = conflict; continue; + } } if (conflict->flags & flags & IORESOURCE_MUXED) { add_wait_queue(&muxed_resource_wait, &wait); Patches currently in stable-queue which might be from simon.guinot@xxxxxxxxxxxx are queue-4.4/kernel-resource.c-fix-muxed-resource-handling-in-__request_region.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html