Messages in this thread | | | Date | Tue, 28 Feb 2023 14:25:31 +0300 | From | Fedor Pchelkin <> | Subject | Re: [PATCH] nfc: fix memory leak of se_io context in nfc_genl_se_io |
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On Tue, Feb 28, 2023 at 11:14:03AM +0100, Krzysztof Kozlowski wrote: > On 27/02/2023 16:05, Fedor Pchelkin wrote: > >>> Fixes: 5ce3f32b5264 ("NFC: netlink: SE API implementation") > >>> Reported-by: syzbot+df64c0a2e8d68e78a4fa@syzkaller.appspotmail.com > >>> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru> > >>> Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> > >> > >> SoB order is a bit odd. Who is the author? > >> > > > > The author is me (Fedor). I thought the authorship is expressed with the > > first Signed-off-by line, isn't it? > > Yes and since you are sending it, then what is Alexey's Sob for? The > tags are in order... >
Now I get what you mean. Alexey is my supervisor and the patches I make are passed through him (even though they are sent by me). If this is not a customary thing, then I'll take that into account for further submissions. I guess something like Acked-by is more appropriate?
> > > >>> --- > >>> drivers/nfc/st-nci/se.c | 6 ++++++ > >>> drivers/nfc/st21nfca/se.c | 6 ++++++ > >>> net/nfc/netlink.c | 4 ++++ > >>> 3 files changed, 16 insertions(+) > >>> > >>> diff --git a/drivers/nfc/st-nci/se.c b/drivers/nfc/st-nci/se.c > >>> index ec87dd21e054..b2f1ced8e6dd 100644 > >>> --- a/drivers/nfc/st-nci/se.c > >>> +++ b/drivers/nfc/st-nci/se.c > >>> @@ -672,6 +672,12 @@ int st_nci_se_io(struct nci_dev *ndev, u32 se_idx, > >>> ST_NCI_EVT_TRANSMIT_DATA, apdu, > >>> apdu_length) > >> nci_hci_send_event() should also free it in its error paths. > >> nci_data_exchange_complete() as well? Who eventually frees it? These > >> might be separate patches. > >> > >> > > > > nci_hci_send_event(), as I can see, should not free the callback context. > > I should have probably better explained that in the commit info (will > > include this in the patch v2), but the main thing is: nfc_se_io() is > > called with se_io_cb callback function as an argument and that callback is > > the exact place where an allocated se_io_ctx context should be freed. And > > it is actually freed there unless some error path happens that leads the > > Exactly, so why nci_hci_send_event() error path should not free it? >
nci_hci_send_event() should not free it on its error path because the bwi_timer is already charged before nci_hci_send_event() is called.
The pattern in the .se_io functions of the corresponding drivers (st-nci, st21nfca) is following:
info->se_info.cb = cb; info->se_info.cb_context = cb_context; mod_timer(&info->se_info.bwi_timer, jiffies + msecs_to_jiffies(info->se_info.wt_timeout)); // <-charged info->se_info.bwi_active = true; return nci_hci_send_event(...);
As the timer is charged, it will eventually call se_io_cb() to free the context, even if the error path is taken inside nci_hci_send_event().
Am I missing something?
> > timer which triggers this se_io_cb callback not to be charged at all. > > > > > Best regards, > Krzysztof >
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