On Wed, Dec 08, 2021 at 10:32:39AM +0100, Mian Yousaf Kaukab wrote:
> During probe ssif_info->client is dereferenced in error path. However,
> it is set when some of the error checking has already been done. This
> causes following kernel crash if an error path is taken:
>
> [ 30.645593][ T674] ipmi_ssif 0-000e: ipmi_ssif: Not probing, Interface
> already present
> [ 30.657616][ T674] Unable to handle kernel NULL pointer dereference at
> virtual address 0000000000000088
> ...
> [ 30.657723][ T674] pc : __dev_printk+0x28/0xa0
> [ 30.657732][ T674] lr : _dev_err+0x7c/0xa0
> ...
> [ 30.657772][ T674] Call trace:
> [ 30.657775][ T674] __dev_printk+0x28/0xa0
> [ 30.657778][ T674] _dev_err+0x7c/0xa0
> [ 30.657781][ T674] ssif_probe+0x548/0x900 [ipmi_ssif
> 62ce4b08badc1458fd896206d9ef69a3c31f3d3e]
> [ 30.657791][ T674] i2c_device_probe+0x37c/0x3c0
> ...
>
> Initialize ssif_info->client before any error path can be taken. Clear
> i2c_client data in the error path to prevent the dangling pointer from
> leaking.
Sigh, I just sent some fixes up to Linus, so this was bound to happen :).
This is in my for-next tree, I'll send it up in a few days if everything
is ok.
Thanks,
-corey
>
> Fixes: c4436c9149c5 ("ipmi_ssif: avoid registering duplicate ssif interface")
> Suggested-by: Takashi Iwai <ti...@suse.de>
> Signed-off-by: Mian Yousaf Kaukab <ykau...@suse.de>
> ---
> drivers/char/ipmi/ipmi_ssif.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 0c62e578749e..48aab77abebf 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -1659,6 +1659,9 @@ static int ssif_probe(struct i2c_client *client, const
> struct i2c_device_id *id)
> }
> }
>
> + ssif_info->client = client;
> + i2c_set_clientdata(client, ssif_info);
> +
> rv = ssif_check_and_remove(client, ssif_info);
> /* If rv is 0 and addr source is not SI_ACPI, continue probing */
> if (!rv && ssif_info->addr_source == SI_ACPI) {
> @@ -1679,9 +1682,6 @@ static int ssif_probe(struct i2c_client *client, const
> struct i2c_device_id *id)
> ipmi_addr_src_to_str(ssif_info->addr_source),
> client->addr, client->adapter->name, slave_addr);
>
> - ssif_info->client = client;
> - i2c_set_clientdata(client, ssif_info);
> -
> /* Now check for system interface capabilities */
> msg[0] = IPMI_NETFN_APP_REQUEST << 2;
> msg[1] = IPMI_GET_SYSTEM_INTERFACE_CAPABILITIES_CMD;
> @@ -1881,6 +1881,7 @@ static int ssif_probe(struct i2c_client *client, const
> struct i2c_device_id *id)
>
> dev_err(&ssif_info->client->dev,
> "Unable to start IPMI SSIF: %d\n", rv);
> + i2c_set_clientdata(client, NULL);
> kfree(ssif_info);
> }
> kfree(resp);
> --
> 2.31.1
>
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