The KASAN allocation trace shows that a malformed IE buffer is stored via SIOCSIWGENIE (cfg80211_wext_siwgenie()) without any validation. The crash trace shows that a subsequent SIOCSIWESSID triggers a connection attempt which calls cfg80211_sme_get_conn_ies() to process the stored IE buffer, causing: - An out-of-bounds read in skip_ie() which reads ies[pos+1] (the length byte) past the end of the 1-byte buffer. - An integer underflow in the memcpy size argument when offs returned by ieee80211_ie_split() exceeds ies_len, causing unsigned subtraction to wrap to SIZE_MAX and triggering a fortify panic. Fix this by validating the IE buffer in cfg80211_wext_siwgenie() before storing it. First reject buffers smaller than 2 bytes since a valid IE requires at least a type and length field. Then use for_each_element() and for_each_element_completed() to verify all elements are well-formed. Return -EINVAL if validation fails. Reported-by: syzbot+cc867e537e4bd36f69bb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=cc867e537e4bd36f69bb Signed-off-by: Deepanshu Kartikey --- v2: Use for_each_element() and for_each_element_completed() instead of open-coded validation loop, as suggested by Johannes Berg. Also add explicit ie_len < 2 check to handle the case where for_each_element_completed() returns true for a 1-byte buffer. --- net/wireless/wext-sme.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/net/wireless/wext-sme.c b/net/wireless/wext-sme.c index 573b6b15a446..51fc2617a1c3 100644 --- a/net/wireless/wext-sme.c +++ b/net/wireless/wext-sme.c @@ -319,6 +319,18 @@ int cfg80211_wext_siwgenie(struct net_device *dev, return 0; if (ie_len) { + const struct element *elem; + + /* IE must have at least Type + Length bytes */ + if (ie_len < 2) + return -EINVAL; + for_each_element(elem, extra, ie_len) { + /* nothing */ + } + + if (!for_each_element_completed(elem, extra, ie_len)) + return -EINVAL; + ie = kmemdup(extra, ie_len, GFP_KERNEL); if (!ie) return -ENOMEM; -- 2.43.0