| Message ID | 20211026180740.1953265-1-mailhol.vincent@wanadoo.fr (mailing list archive) |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v1] can: etas_es58x: es58x_rx_err_msg: fix memory leak in error path | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Series ignored based on subject |
On 27.10.2021 03:07:40, Vincent Mailhol wrote: > In es58x_rx_err_msg(), if can->do_set_mode() fails, the function > directly returns without calling netif_rx(skb). This means that the > skb previously allocated by alloc_can_err_skb() is not freed. In other > terms, this is a memory leak. > > This patch simply removes the return statement in the error branch and > let the function continue. > > * Appendix: how the issue was found * Thanks for the explanation, but I think I'll remove the appendix while applying. Thanks, Marc
On Wed. 27 Oct 2021 at 16:39, Marc Kleine-Budde <mkl@pengutronix.de> wrote: > On 27.10.2021 03:07:40, Vincent Mailhol wrote: > > In es58x_rx_err_msg(), if can->do_set_mode() fails, the function > > directly returns without calling netif_rx(skb). This means that the > > skb previously allocated by alloc_can_err_skb() is not freed. In other > > terms, this is a memory leak. > > > > This patch simply removes the return statement in the error branch and > > let the function continue. > > > > * Appendix: how the issue was found * > > Thanks for the explanation, but I think I'll remove the appendix while > applying. The commit will have a link to this thread so if you don't mind, I suggest to replace the full appendix with: Issue was found with GCC -fanalyzer, please follow the link below for details. You can of course do the same for the m_can patch. Yours sincerely, Vincent Mailhol
On 27.10.2021 17:48:21, Vincent MAILHOL wrote: > On Wed. 27 Oct 2021 at 16:39, Marc Kleine-Budde <mkl@pengutronix.de> wrote: > > On 27.10.2021 03:07:40, Vincent Mailhol wrote: > > > In es58x_rx_err_msg(), if can->do_set_mode() fails, the function > > > directly returns without calling netif_rx(skb). This means that the > > > skb previously allocated by alloc_can_err_skb() is not freed. In other > > > terms, this is a memory leak. > > > > > > This patch simply removes the return statement in the error branch and > > > let the function continue. > > > > > > * Appendix: how the issue was found * > > > > Thanks for the explanation, but I think I'll remove the appendix while > > applying. > > The commit will have a link to this thread so if you don't mind, > I suggest to replace the full appendix with: > > Issue was found with GCC -fanalyzer, please follow the link below > for details. Makes sense, good idea. > You can of course do the same for the m_can patch. ACK Added to linux-can/testing, will send it out once v5.15 is out. Thanks, Marc
diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c index 403de7e9d084..8508a73d648e 100644 --- a/drivers/net/can/usb/etas_es58x/es58x_core.c +++ b/drivers/net/can/usb/etas_es58x/es58x_core.c @@ -664,7 +664,7 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error, struct can_device_stats *can_stats = &can->can_stats; struct can_frame *cf = NULL; struct sk_buff *skb; - int ret; + int ret = 0; if (!netif_running(netdev)) { if (net_ratelimit()) @@ -823,8 +823,6 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error, can->state = CAN_STATE_BUS_OFF; can_bus_off(netdev); ret = can->do_set_mode(netdev, CAN_MODE_STOP); - if (ret) - return ret; } break; @@ -881,7 +879,7 @@ int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error, ES58X_EVENT_BUSOFF, timestamp); } - return 0; + return ret; } /**
In es58x_rx_err_msg(), if can->do_set_mode() fails, the function directly returns without calling netif_rx(skb). This means that the skb previously allocated by alloc_can_err_skb() is not freed. In other terms, this is a memory leak. This patch simply removes the return statement in the error branch and let the function continue. * Appendix: how the issue was found * This issue was found using GCC's static analysis tool: -fanalyzer: https://gcc.gnu.org/onlinedocs/gcc/Static-Analyzer-Options.html The step to reproduce are: 1. Install GCC 11. 2. Hack the kernel's Makefile to add the -fanalyzer flag (we leave it as an exercise for the reader to figure out the details of how to do so). 3. Decorate the function alloc_can_err_skb() with __attribute__((__malloc__ (dealloc, netif_rx))). This step helps the static analyzer to figure out the constructor/destructor pairs (not something it can deduce by himself). 4. Compile. The compiler then throws below warning: | In function 'es58x_rx_err_msg': | drivers/net/can/usb/etas_es58x/es58x_core.c:826:28: warning: leak of 'skb' [CWE-401] [-Wanalyzer-malloc-leak] | 826 | if (ret) | | ^ | 'es58x_rx_err_msg': events 1-9 | | | | 659 | int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error, | | | ^~~~~~~~~~~~~~~~ | | | | | | | (1) entry to 'es58x_rx_err_msg' | |...... | | 669 | if (!netif_running(netdev)) { | | | ~ | | | | | | | (2) following 'true' branch... | |...... | | 677 | if (error == ES58X_ERR_OK && event == ES58X_EVENT_OK) { | | | ~~ ~ | | | | | | | | | (4) following 'false' branch... | | | (3) ...to here | |...... | | 683 | skb = alloc_can_err_skb(netdev, &cf); | | | ~~~ | | | | | | | (5) ...to here | |...... | | 861 | if (cf) { | | | ~ | | | | | | | (6) following 'false' branch... | |...... | | 875 | if ((event & ES58X_EVENT_CRTL_PASSIVE) && | | | ~~ ~ | | | | | | | | | (8) following 'true' branch... | | | (7) ...to here | | 876 | priv->err_passive_before_rtx_success == ES58X_CONSECUTIVE_ERR_PASSIVE_MAX) { | | | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | | | (9) ...to here | | | 'es58x_rx_err_msg': events 10-12 | | | | 875 | if ((event & ES58X_EVENT_CRTL_PASSIVE) && | | 876 | priv->err_passive_before_rtx_success == ES58X_CONSECUTIVE_ERR_PASSIVE_MAX) { | | 877 | netdev_info(netdev, | | | ~~~~~~~~~~~ | | | | | | | (11) ...to here | |...... | | 880 | return es58x_rx_err_msg(netdev, ES58X_ERR_OK, | | | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | | | (12) calling 'es58x_rx_err_msg' from 'es58x_rx_err_msg' | | 881 | ES58X_EVENT_BUSOFF, timestamp); | | | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | +--> 'es58x_rx_err_msg': events 13-23 | | | | 659 | int es58x_rx_err_msg(struct net_device *netdev, enum es58x_err error, | | | ^~~~~~~~~~~~~~~~ | | | | | | | (13) entry to 'es58x_rx_err_msg' | |...... | | 669 | if (!netif_running(netdev)) { | | | ~ | | | | | | | (14) following 'true' branch... | |...... | | 677 | if (error == ES58X_ERR_OK && event == ES58X_EVENT_OK) { | | | ~~ ~ | | | | | | | | | (16) following 'false' branch... | | | (15) ...to here | |...... | | 683 | skb = alloc_can_err_skb(netdev, &cf); | | | ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | | | | | | | | (18) allocated here | | | (17) ...to here | | 684 | | | 685 | switch (error) { | | | ~~~~~~ | | | | | | | (19) following 'case 0:' branch... | |...... | | 764 | switch (event) { | | | ~~~~~~ | | | | | | | (20) ...to here | | | (21) following 'case 8:' branch... | |...... | | 815 | case ES58X_EVENT_BUSOFF: | | | ~~~~ | | | | | | | (22) ...to here | |...... | | 826 | if (ret) | | | ~ | | | | | | | (23) 'skb' leaks here; was allocated at (18) | | Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces") Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> --- drivers/net/can/usb/etas_es58x/es58x_core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)