switchtec: Fix potential Spectre v1
Subsystems (2)
PATCH 1/1 switchtec: Fix potential Spectre v1
p.port can is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/pci/switch/switchtec.c:912 ioctl_port_to_pff() warn: potential spectre issue 'pcfg->dsp_pff_inst_id' [r]
Fix this by sanitizing p.port before using it to index pcfg->dsp_pff_inst_id
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://marc.info/?l=linux-kernel&m=152449131114778&w=2
--- drivers/pci/switch/switchtec.c | 4 ++++ 1 file changed, 4 insertions(+)
drivers/pci/switch/switchtec.c +4 -0
@@ -14,6 +14,8 @@#include <linux/poll.h> #include <linux/wait.h> +#include <linux/nospec.h> +MODULE_DESCRIPTION ("Microsemi Switchtec(tm) PCIe Management Driver" );MODULE_VERSION ("0.1" );MODULE_LICENSE ("GPL" );
@@ -909,6 +911,8 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev,default :if (p.port >ARRAY_SIZE (pcfg->dsp_pff_inst_id))return -EINVAL ; + p.port =array_index_nospec (p.port, +ARRAY_SIZE (pcfg->dsp_pff_inst_id) +1 ); p.pff =ioread32 (&pcfg->dsp_pff_inst_id[p.port -1 ]);break ; }
Signature · 1 line
2.7.4
Quoted 11 lines · Gustavo A. R. Silva
p.port can is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/pci/switch/switchtec.c:912ioctl_port_to_pff()warn: potential spectre issue 'pcfg->dsp_pff_inst_id' [r]Fix this by sanitizing p.port before using it to index
pcfg->dsp_pff_inst_id
Quoted 8 lines
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://marc.info/?l=linux-kernel&m=152449131114778&w=2
Signed-off-by Gustavo A. R. Silva <[email protected]>
Looks good to me, thanks.
Logan
Quoted 11 lines · Gustavo A. R. Silva
p.port can is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability.
This issue was detected with the help of Smatch:
drivers/pci/switch/switchtec.c:912ioctl_port_to_pff()warn: potential spectre issue 'pcfg->dsp_pff_inst_id' [r]Fix this by sanitizing p.port before using it to index
pcfg->dsp_pff_inst_id
Quoted 8 lines
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://marc.info/?l=linux-kernel&m=152449131114778&w=2
Signed-off-by Gustavo A. R. Silva <[email protected]>
Applied with Logan's ack to for-linus for v4.19, thanks!
Quoted 29 lines
--- drivers/pci/switch/switchtec.c | 4 ++++ 1 file changed, 4 insertions(+)drivers/pci/switch/switchtec.c +4
-0@@ -14,6 +14,8 @@#include <linux/poll.h> #include <linux/wait.h> +#include <linux/nospec.h> +MODULE_DESCRIPTION ("Microsemi Switchtec(tm) PCIe Management Driver" );MODULE_VERSION ("0.1" );MODULE_LICENSE ("GPL" );@@ -909,6 +911,8 @@ static int ioctl_port_to_pff(struct switchtec_dev *stdev,default :if (p.port >ARRAY_SIZE (pcfg->dsp_pff_inst_id))return -EINVAL ; + p.port =array_index_nospec (p.port, +ARRAY_SIZE (pcfg->dsp_pff_inst_id) +1 ); p.pff =ioread32 (&pcfg->dsp_pff_inst_id[p.port -1 ]);break ; }Signature · 1 line
2.7.4