mac80211: fix use-after-free in CCMP/GCMP RX

stable inclusion
from stable-v4.19.209
commit 3d5d629c99c468458022e9b381789de3595bf4dd
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9R4NV
CVE: CVE-2021-47388

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3d5d629c99c468458022e9b381789de3595bf4dd

--------------------------------

commit 94513069 upstream.

When PN checking is done in mac80211, for fragmentation we need
to copy the PN to the RX struct so we can later use it to do a
comparison, since commit bf30ca92 ("mac80211: check defrag
PN against current frame").

Unfortunately, in that commit I used the 'hdr' variable without
it being necessarily valid, so use-after-free could occur if it
was necessary to reallocate (parts of) the frame.

Fix this by reloading the variable after the code that results
in the reallocations, if any.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=214401.

Cc: stable@vger.kernel.org
Fixes: bf30ca92 ("mac80211: check defrag PN against current frame")
Link: https://lore.kernel.org/r/20210927115838.12b9ac6bb233.I1d066acd5408a662c3b6e828122cd314fcb28cdb@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>