Patch "cfg80211: Fix array-bounds warning in fragment copy" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

cfg80211: Fix array-bounds warning in fragment copy

to the 4.9-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:
cfg80211-fix-array-bounds-warning-in-fragment-copy.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Matthias Kaehlcke <[email protected]>
Date: Thu, 13 Apr 2017 10:05:04 -0700
Subject: cfg80211: Fix array-bounds warning in fragment copy

From: Matthias Kaehlcke <[email protected]>

commit aa1702dd162f420bf85ecef0c77686ef0dbc1496 upstream.

__ieee80211_amsdu_copy_frag intentionally initializes a pointer to array[-1] to increment it later to valid values. clang rightfully generates an array-bounds warning on the initialization statement.

Initialize the pointer to array[0] and change the algorithm from increment before to increment after consume.

---
 net/wireless/util.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

@@ -663,7 +663,7 @@ __ieee80211_amsdu_copy_frag(struct sk_bu
 			    int offset, int len)
 {
 	struct skb_shared_info *sh = skb_shinfo(skb);
-	const skb_frag_t *frag = &sh->frags[-1];
+	const skb_frag_t *frag = &sh->frags[0];
 	struct page *frag_page;
 	void *frag_ptr;
 	int frag_len, frag_size;

@@ -676,10 +676,10 @@ __ieee80211_amsdu_copy_frag(struct sk_bu
 
 	while (offset >= frag_size) {
 		offset -= frag_size;
-		frag++;
 		frag_page = skb_frag_page(frag);
 		frag_ptr = skb_frag_address(frag);
 		frag_size = skb_frag_size(frag);
+		frag++;
 	}
 
 	frag_ptr += offset;

@@ -691,12 +691,12 @@ __ieee80211_amsdu_copy_frag(struct sk_bu
 	len -= cur_len;
 
 	while (len > 0) {
-		frag++;
 		frag_len = skb_frag_size(frag);
 		cur_len = min(len, frag_len);
 		__frame_add_frag(frame, skb_frag_page(frag),
 				 skb_frag_address(frag), cur_len, frag_len);
 		len -= cur_len;
+		frag++;
 	}
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/dm-ioctl-remove-double-parentheses.patch queue-4.9/arm64-avoid-overflow-in-va_start-and-page_offset.patch queue-4.9/btrfs-remove-extra-parentheses-from-condition-in-copy_items.patch queue-4.9/genirq-use-cpumask_available-for-check-of-cpumask-variable.patch queue-4.9/nl80211-fix-enum-type-of-variable-in-nl80211_put_sta_rate.patch queue-4.9/selinux-remove-redundant-check-for-unknown-labeling-behavior.patch queue-4.9/fs-compat-remove-warning-from-compatible_ioctl.patch queue-4.9/jiffies.h-declare-jiffies-and-jiffies_64-with-____cacheline_aligned_in_smp.patch queue-4.9/selinux-remove-unnecessary-check-of-array-base-in-selinux_set_mapping.patch queue-4.9/pci-make-pci_rom_address_mask-a-32-bit-constant.patch queue-4.9/frv-declare-jiffies-to-be-located-in-the-.data-section.patch queue-4.9/mac80211-ibss-fix-channel-type-enum-in-ieee80211_sta_join_ibss.patch queue-4.9/cfg80211-fix-array-bounds-warning-in-fragment-copy.patch queue-4.9/netfilter-ctnetlink-make-some-parameters-integer-to-avoid-enum-mismatch.patch queue-4.9/mac80211-fix-clang-warning-about-constant-operand-in-logical-operation.patch queue-4.9/cpumask-add-helper-cpumask_available.patch