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author | Julius Werner <jwerner@chromium.org> | 2012-11-01 12:47:59 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-21 11:44:59 -0800 |
commit | 3b2167cc50f31531ee7cae375801489d1105d547 (patch) | |
tree | f1c3d98863b890803a079f5a511e4f15b7c10bef | |
parent | 2ff95abca6fe594a7c9182d96fa4aa37997c4a86 (diff) | |
download | kernel_samsung_smdk4412-3b2167cc50f31531ee7cae375801489d1105d547.zip kernel_samsung_smdk4412-3b2167cc50f31531ee7cae375801489d1105d547.tar.gz kernel_samsung_smdk4412-3b2167cc50f31531ee7cae375801489d1105d547.tar.bz2 |
xhci: fix null-pointer dereference when destroying half-built segment rings
commit 68e5254adb88bede68285f11fb442a4d34fb550c upstream.
xhci_alloc_segments_for_ring() builds a list of xhci_segments and links
the tail to head at the end (forming a ring). When it bails out for OOM
reasons half-way through, it tries to destroy its half-built list with
xhci_free_segments_for_ring(), even though it is not a ring yet. This
causes a null-pointer dereference upon hitting the last element.
Furthermore, one of its callers (xhci_ring_alloc()) mistakenly believes
the output parameters to be valid upon this kind of OOM failure, and
calls xhci_ring_free() on them. Since the (incomplete) list/ring should
already be destroyed in that case, this would lead to a use after free.
This patch fixes those issues by having xhci_alloc_segments_for_ring()
destroy its half-built, non-circular list manually and destroying the
invalid struct xhci_ring in xhci_ring_alloc() with a plain kfree().
This patch should be backported to kernels as old as 2.6.31, that
contains the commit 0ebbab37422315a5d0cb29792271085bafdf38c0 "USB: xhci:
Ring allocation and initialization."
A separate patch will need to be developed for kernels older than 3.4,
since the ring allocation code was refactored in that kernel.
Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
[bwh: Backported to 3.2:
- Adjust context
- Since segment allocation is done directly in xhci_ring_alloc(), walk
the list starting from ring->first_seg when freeing]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/usb/host/xhci-mem.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index a2b20fe..af65322 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -180,8 +180,15 @@ static struct xhci_ring *xhci_ring_alloc(struct xhci_hcd *xhci, struct xhci_segment *next; next = xhci_segment_alloc(xhci, flags); - if (!next) + if (!next) { + prev = ring->first_seg; + while (prev) { + next = prev->next; + xhci_segment_free(xhci, prev); + prev = next; + } goto fail; + } xhci_link_segments(xhci, prev, next, link_trbs, isoc); prev = next; @@ -201,7 +208,7 @@ static struct xhci_ring *xhci_ring_alloc(struct xhci_hcd *xhci, return ring; fail: - xhci_ring_free(xhci, ring); + kfree(ring); return NULL; } |