4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> commit a7102c7461794a5bb31af24b08e9e0f50038897a upstream. channel and addr->channel are indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. These issues were detected with the help of Smatch: drivers/char/ipmi/ipmi_msghandler.c:1381 ipmi_set_my_address() warn: potential spectre issue 'user->intf->addrinfo' [w] (local cap) drivers/char/ipmi/ipmi_msghandler.c:1401 ipmi_get_my_address() warn: potential spectre issue 'user->intf->addrinfo' [r] (local cap) drivers/char/ipmi/ipmi_msghandler.c:1421 ipmi_set_my_LUN() warn: potential spectre issue 'user->intf->addrinfo' [w] (local cap) drivers/char/ipmi/ipmi_msghandler.c:1441 ipmi_get_my_LUN() warn: potential spectre issue 'user->intf->addrinfo' [r] (local cap) drivers/char/ipmi/ipmi_msghandler.c:2260 check_addr() warn: potential spectre issue 'intf->addrinfo' [r] (local cap) Fix this by sanitizing channel and addr->channel before using them to index user->intf->addrinfo and intf->addrinfo, correspondingly. Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://lore.kernel.org/lkml/20180423164740.GY17484@xxxxxxxxxxxxxx/ Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx> Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/char/ipmi/ipmi_msghandler.c | 26 ++++++++++++++++++-------- 1 file changed, 18 insertions(+), 8 deletions(-) --- a/drivers/char/ipmi/ipmi_msghandler.c +++ b/drivers/char/ipmi/ipmi_msghandler.c @@ -32,6 +32,7 @@ #include <linux/moduleparam.h> #include <linux/workqueue.h> #include <linux/uuid.h> +#include <linux/nospec.h> #define IPMI_DRIVER_VERSION "39.2" @@ -1298,10 +1299,12 @@ int ipmi_set_my_address(struct ipmi_user if (!user) return -ENODEV; - if (channel >= IPMI_MAX_CHANNELS) + if (channel >= IPMI_MAX_CHANNELS) { rv = -EINVAL; - else + } else { + channel = array_index_nospec(channel, IPMI_MAX_CHANNELS); user->intf->addrinfo[channel].address = address; + } release_ipmi_user(user, index); return rv; @@ -1318,10 +1321,12 @@ int ipmi_get_my_address(struct ipmi_user if (!user) return -ENODEV; - if (channel >= IPMI_MAX_CHANNELS) + if (channel >= IPMI_MAX_CHANNELS) { rv = -EINVAL; - else + } else { + channel = array_index_nospec(channel, IPMI_MAX_CHANNELS); *address = user->intf->addrinfo[channel].address; + } release_ipmi_user(user, index); return rv; @@ -1338,10 +1343,12 @@ int ipmi_set_my_LUN(struct ipmi_user *us if (!user) return -ENODEV; - if (channel >= IPMI_MAX_CHANNELS) + if (channel >= IPMI_MAX_CHANNELS) { rv = -EINVAL; - else + } else { + channel = array_index_nospec(channel, IPMI_MAX_CHANNELS); user->intf->addrinfo[channel].lun = LUN & 0x3; + } release_ipmi_user(user, index); return rv; @@ -1358,10 +1365,12 @@ int ipmi_get_my_LUN(struct ipmi_user *us if (!user) return -ENODEV; - if (channel >= IPMI_MAX_CHANNELS) + if (channel >= IPMI_MAX_CHANNELS) { rv = -EINVAL; - else + } else { + channel = array_index_nospec(channel, IPMI_MAX_CHANNELS); *address = user->intf->addrinfo[channel].lun; + } release_ipmi_user(user, index); return rv; @@ -2184,6 +2193,7 @@ static int check_addr(struct ipmi_smi * { if (addr->channel >= IPMI_MAX_CHANNELS) return -EINVAL; + addr->channel = array_index_nospec(addr->channel, IPMI_MAX_CHANNELS); *lun = intf->addrinfo[addr->channel].lun; *saddr = intf->addrinfo[addr->channel].address; return 0;
