| Message ID | 20210713054019.409273-1-mudongliangabcd@gmail.com (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | ieee802154: hwsim: fix memory leak in __pskb_copy_fclone | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Guessed tree name to be net-next |
| netdev/subject_prefix | warning | Target tree name not specified in the subject |
| netdev/cc_maintainers | success | CCed 6 of 6 maintainers |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 12 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
Hi, On Tue, 13 Jul 2021 at 01:40, Dongliang Mu <mudongliangabcd@gmail.com> wrote: > > hwsim_hw_xmit fails to deallocate the newskb copied by pskb_copy. Fix > this by adding kfree_skb after ieee802154_rx_irqsafe. > > [<ffffffff836433fb>] __alloc_skb+0x22b/0x250 net/core/skbuff.c:414 > [<ffffffff8364ad95>] __pskb_copy_fclone+0x75/0x360 net/core/skbuff.c:1609 > [<ffffffff82ae65e3>] __pskb_copy include/linux/skbuff.h:1176 [inline] > [<ffffffff82ae65e3>] pskb_copy include/linux/skbuff.h:3207 [inline] > [<ffffffff82ae65e3>] hwsim_hw_xmit+0xd3/0x140 drivers/net/ieee802154/mac802154_hwsim.c:132 > [<ffffffff83ff8f47>] drv_xmit_async net/mac802154/driver-ops.h:16 [inline] > [<ffffffff83ff8f47>] ieee802154_tx+0xc7/0x190 net/mac802154/tx.c:83 > [<ffffffff83ff9138>] ieee802154_subif_start_xmit+0x58/0x70 net/mac802154/tx.c:132 > [<ffffffff83670b82>] __netdev_start_xmit include/linux/netdevice.h:4944 [inline] > [<ffffffff83670b82>] netdev_start_xmit include/linux/netdevice.h:4958 [inline] > [<ffffffff83670b82>] xmit_one net/core/dev.c:3658 [inline] > [<ffffffff83670b82>] dev_hard_start_xmit+0xe2/0x330 net/core/dev.c:3674 > [<ffffffff83718028>] sch_direct_xmit+0xf8/0x520 net/sched/sch_generic.c:342 > [<ffffffff8367193b>] __dev_xmit_skb net/core/dev.c:3874 [inline] > [<ffffffff8367193b>] __dev_queue_xmit+0xa3b/0x1360 net/core/dev.c:4241 > [<ffffffff83ff5437>] dgram_sendmsg+0x437/0x570 net/ieee802154/socket.c:682 > [<ffffffff836345b6>] sock_sendmsg_nosec net/socket.c:702 [inline] > [<ffffffff836345b6>] sock_sendmsg+0x56/0x80 net/socket.c:722 > > Fixes: f25da51fdc38 ("ieee802154: hwsim: add replacement for fakelb") > Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com> sorry, I don't get the fix. Is this a memory leak? I remember there was something reported by syzkaller [0] but I wasn't able yet to get into it. Is it what you referring to? __pskb_copy_fclone() shows "The returned buffer has a reference count of 1" and ieee802154_rx_irqsafe() will queue the skb for a tasklet. With your patch it will be immediately freed and a use after free will occur. I believe there is something wrong in the error path of 802.15.4 frame parsing and that's why we sometimes have a leaks there. I need to test this patch, but I don't get how this patch is supposed to fix the issue. - Alex [0] https://groups.google.com/g/syzkaller-bugs/c/EoIvZbk3Zfo/m/AlKUiErlAwAJ
On Tue, Jul 13, 2021 at 9:47 PM Alexander Aring <alex.aring@gmail.com> wrote: > > Hi, > > On Tue, 13 Jul 2021 at 01:40, Dongliang Mu <mudongliangabcd@gmail.com> wrote: > > > > hwsim_hw_xmit fails to deallocate the newskb copied by pskb_copy. Fix > > this by adding kfree_skb after ieee802154_rx_irqsafe. > > > > [<ffffffff836433fb>] __alloc_skb+0x22b/0x250 net/core/skbuff.c:414 > > [<ffffffff8364ad95>] __pskb_copy_fclone+0x75/0x360 net/core/skbuff.c:1609 > > [<ffffffff82ae65e3>] __pskb_copy include/linux/skbuff.h:1176 [inline] > > [<ffffffff82ae65e3>] pskb_copy include/linux/skbuff.h:3207 [inline] > > [<ffffffff82ae65e3>] hwsim_hw_xmit+0xd3/0x140 drivers/net/ieee802154/mac802154_hwsim.c:132 > > [<ffffffff83ff8f47>] drv_xmit_async net/mac802154/driver-ops.h:16 [inline] > > [<ffffffff83ff8f47>] ieee802154_tx+0xc7/0x190 net/mac802154/tx.c:83 > > [<ffffffff83ff9138>] ieee802154_subif_start_xmit+0x58/0x70 net/mac802154/tx.c:132 > > [<ffffffff83670b82>] __netdev_start_xmit include/linux/netdevice.h:4944 [inline] > > [<ffffffff83670b82>] netdev_start_xmit include/linux/netdevice.h:4958 [inline] > > [<ffffffff83670b82>] xmit_one net/core/dev.c:3658 [inline] > > [<ffffffff83670b82>] dev_hard_start_xmit+0xe2/0x330 net/core/dev.c:3674 > > [<ffffffff83718028>] sch_direct_xmit+0xf8/0x520 net/sched/sch_generic.c:342 > > [<ffffffff8367193b>] __dev_xmit_skb net/core/dev.c:3874 [inline] > > [<ffffffff8367193b>] __dev_queue_xmit+0xa3b/0x1360 net/core/dev.c:4241 > > [<ffffffff83ff5437>] dgram_sendmsg+0x437/0x570 net/ieee802154/socket.c:682 > > [<ffffffff836345b6>] sock_sendmsg_nosec net/socket.c:702 [inline] > > [<ffffffff836345b6>] sock_sendmsg+0x56/0x80 net/socket.c:722 > > > > Fixes: f25da51fdc38 ("ieee802154: hwsim: add replacement for fakelb") > > Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com> > > sorry, I don't get the fix. Is this a memory leak? I remember there > was something reported by syzkaller [0] but I wasn't able yet to get > into it. Is it what you referring to? Yes, you're right. I get this memory leak many times in my local syzkaller instance but do not recognize there is already a bug report in the syzbot dashboard. > __pskb_copy_fclone() shows "The returned buffer has a reference count > of 1" and ieee802154_rx_irqsafe() will queue the skb for a tasklet. > With your patch it will be immediately freed and a use after free will > occur. Thanks for your feedback. I am sorry about this fix since I did not observe UAF in my testing. I will keep learning more materials about socket in Linux kernel. :) > I believe there is something wrong in the error path of > 802.15.4 frame parsing and that's why we sometimes have a leaks there. Should be yes, it occurs many times in my local syzkaller instance. > > I need to test this patch, but I don't get how this patch is supposed > to fix the issue. This patch should be incorrect. Please directly focus on bug reports on the syzbot dashboard. If possible, please cc me your final patch about this bug. I can learn something from this bug. Best regards Dongliang Mu > > - Alex > > [0] https://groups.google.com/g/syzkaller-bugs/c/EoIvZbk3Zfo/m/AlKUiErlAwAJ
diff --git a/drivers/net/ieee802154/mac802154_hwsim.c b/drivers/net/ieee802154/mac802154_hwsim.c index ebc976b7fcc2..d97ed033ac77 100644 --- a/drivers/net/ieee802154/mac802154_hwsim.c +++ b/drivers/net/ieee802154/mac802154_hwsim.c @@ -132,9 +132,11 @@ static int hwsim_hw_xmit(struct ieee802154_hw *hw, struct sk_buff *skb) struct sk_buff *newskb = pskb_copy(skb, GFP_ATOMIC); einfo = rcu_dereference(e->info); - if (newskb) + if (newskb) { ieee802154_rx_irqsafe(e->endpoint->hw, newskb, einfo->lqi); + kfree_skb(newskb); + } } } rcu_read_unlock();
hwsim_hw_xmit fails to deallocate the newskb copied by pskb_copy. Fix this by adding kfree_skb after ieee802154_rx_irqsafe. [<ffffffff836433fb>] __alloc_skb+0x22b/0x250 net/core/skbuff.c:414 [<ffffffff8364ad95>] __pskb_copy_fclone+0x75/0x360 net/core/skbuff.c:1609 [<ffffffff82ae65e3>] __pskb_copy include/linux/skbuff.h:1176 [inline] [<ffffffff82ae65e3>] pskb_copy include/linux/skbuff.h:3207 [inline] [<ffffffff82ae65e3>] hwsim_hw_xmit+0xd3/0x140 drivers/net/ieee802154/mac802154_hwsim.c:132 [<ffffffff83ff8f47>] drv_xmit_async net/mac802154/driver-ops.h:16 [inline] [<ffffffff83ff8f47>] ieee802154_tx+0xc7/0x190 net/mac802154/tx.c:83 [<ffffffff83ff9138>] ieee802154_subif_start_xmit+0x58/0x70 net/mac802154/tx.c:132 [<ffffffff83670b82>] __netdev_start_xmit include/linux/netdevice.h:4944 [inline] [<ffffffff83670b82>] netdev_start_xmit include/linux/netdevice.h:4958 [inline] [<ffffffff83670b82>] xmit_one net/core/dev.c:3658 [inline] [<ffffffff83670b82>] dev_hard_start_xmit+0xe2/0x330 net/core/dev.c:3674 [<ffffffff83718028>] sch_direct_xmit+0xf8/0x520 net/sched/sch_generic.c:342 [<ffffffff8367193b>] __dev_xmit_skb net/core/dev.c:3874 [inline] [<ffffffff8367193b>] __dev_queue_xmit+0xa3b/0x1360 net/core/dev.c:4241 [<ffffffff83ff5437>] dgram_sendmsg+0x437/0x570 net/ieee802154/socket.c:682 [<ffffffff836345b6>] sock_sendmsg_nosec net/socket.c:702 [inline] [<ffffffff836345b6>] sock_sendmsg+0x56/0x80 net/socket.c:722 Fixes: f25da51fdc38 ("ieee802154: hwsim: add replacement for fakelb") Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com> --- drivers/net/ieee802154/mac802154_hwsim.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)