CVE-2024-41040

In the Linux kernel, the following vulnerability has been resolved:

net/sched: Fix UAF when resolving a clash

KASAN reports the following UAF:

BUG: KASAN: slab-use-after-free in tcfctflowtableprocessconn+0x12b/0x380 [actct] Read of size 1 at addr ffff888c07603600 by task handler130/6469

Call Trace: <IRQ> dumpstacklvl+0x48/0x70 printaddressdescription.constprop.0+0x33/0x3d0 printreport+0xc0/0x2b0 kasanreport+0xd0/0x120 __asanload1+0x6c/0x80 tcfctflowtableprocessconn+0x12b/0x380 [actct] tcfctact+0x886/0x1350 [actct] tcfactionexec+0xf8/0x1f0 flclassify+0x355/0x360 [clsflower] __tcfclassify+0x1fd/0x330 tcfclassify+0x21c/0x3c0 schhandleingress.constprop.0+0x2c5/0x500 __netifreceiveskb_core.constprop.0+0xb25/0x1510 __netifreceiveskblistcore+0x220/0x4c0 netifreceiveskblistinternal+0x446/0x620 napicompletedone+0x157/0x3d0 grocellpoll+0xcf/0x100 __napipoll+0x65/0x310 netrx_action+0x30c/0x5c0 __do_softirq+0x14f/0x491 _irqexitrcu+0x82/0xc0 irqexitrcu+0xe/0x20 commoninterrupt+0xa1/0xb0 </IRQ> <TASK> asmcommoninterrupt+0x27/0x40

Allocated by task 6469: kasansavestack+0x38/0x70 kasansettrack+0x25/0x40 kasansavealloc_info+0x1e/0x40 __kasankrealloc+0x133/0x190 krealloc+0xaa/0x130 nfctextadd+0xed/0x230 [nfconntrack] tcfctact+0x1095/0x1350 [actct] tcfactionexec+0xf8/0x1f0 flclassify+0x355/0x360 [clsflower] __tcfclassify+0x1fd/0x330 tcfclassify+0x21c/0x3c0 schhandleingress.constprop.0+0x2c5/0x500 __netifreceiveskb_core.constprop.0+0xb25/0x1510 __netifreceiveskblistcore+0x220/0x4c0 netifreceiveskblistinternal+0x446/0x620 napicompletedone+0x157/0x3d0 grocellpoll+0xcf/0x100 __napipoll+0x65/0x310 netrx_action+0x30c/0x5c0 _dosoftirq+0x14f/0x491

Freed by task 6469: kasansavestack+0x38/0x70 kasansettrack+0x25/0x40 kasansavefree_info+0x2b/0x60 ____kasanslabfree+0x180/0x1f0 __kasanslabfree+0x12/0x30 slabfreefreelist_hook+0xd2/0x1a0 __kmemcachefree+0x1a2/0x2f0 kfree+0x78/0x120 nfconntrackfree+0x74/0x130 [nfconntrack] nfctdestroy+0xb2/0x140 [nfconntrack] __nfctresolveclash+0x529/0x5d0 [nfconntrack] nfctresolveclash+0xf6/0x490 [nfconntrack] __nfconntrackconfirm+0x2c6/0x770 [nfconntrack] tcfctact+0x12ad/0x1350 [actct] tcfactionexec+0xf8/0x1f0 flclassify+0x355/0x360 [clsflower] __tcfclassify+0x1fd/0x330 tcfclassify+0x21c/0x3c0 schhandleingress.constprop.0+0x2c5/0x500 __netifreceiveskb_core.constprop.0+0xb25/0x1510 __netifreceiveskblistcore+0x220/0x4c0 netifreceiveskblistinternal+0x446/0x620 napicompletedone+0x157/0x3d0 grocellpoll+0xcf/0x100 __napipoll+0x65/0x310 netrx_action+0x30c/0x5c0 _dosoftirq+0x14f/0x491

The ct may be dropped if a clash has been resolved but is still passed to the tcfctflowtableprocess_conn function for further usage. This issue can be fixed by retrieving ct from skb again after confirming conntrack.