| Message ID | 20190730084047.26482-1-hslester96@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | scsi: 3w-sas: Fix unterminated strncpy | expand |
On Tue, 2019-07-30 at 16:40 +0800, Chuhong Yuan wrote: > strncpy(dest, src, strlen(src)) leads to unterminated > dest, which is dangerous. I don't buy that. The structure is only used for the TW_IOCTL_GET_COMPATIBILITY_INFO ioctl and all the fields for that are fixed width and are copied over as such. > Here driver_version's len is 32 and TW_DRIVER_VERSION > is shorter than 32. > Therefore strcpy is OK. The best practice for copying a string to a fixed width destination that does get printed within the kernel would be what the 3w-9xxx.c does strlcpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION, sizeof(tw_dev->tw_compat_info.driver_version)); But as I said, it doesn't really matter for a fixed width field that's never printed within the kernel. James
On Tue, Jul 30, 2019 at 10:56 PM James Bottomley <jejb@linux.ibm.com> wrote: > > On Tue, 2019-07-30 at 16:40 +0800, Chuhong Yuan wrote: > > strncpy(dest, src, strlen(src)) leads to unterminated > > dest, which is dangerous. > > I don't buy that. The structure is only used for the > TW_IOCTL_GET_COMPATIBILITY_INFO ioctl and all the fields for that are > fixed width and are copied over as such. > > > Here driver_version's len is 32 and TW_DRIVER_VERSION > > is shorter than 32. > > Therefore strcpy is OK. > > The best practice for copying a string to a fixed width destination > that does get printed within the kernel would be what the 3w-9xxx.c > does > > strlcpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION, > sizeof(tw_dev->tw_compat_info.driver_version)); > This is right, and strscpy() is better than strlcpy(). strlcpy() is deprecated now according to the documentation. I choose strcpy() since it has better performance and there is no worry of overflow here. And I find there are indeed some places using strcpy() to fix this problem, like add_man_viewer() in tools/perf/builtin-help.c. > But as I said, it doesn't really matter for a fixed width field that's > never printed within the kernel. > I think it is not good to leave a exploitable place here, and fixing it does not need much effort. Regards, Chuhong > James >
diff --git a/drivers/scsi/3w-sas.c b/drivers/scsi/3w-sas.c index dda6fa857709..96f529c613a6 100644 --- a/drivers/scsi/3w-sas.c +++ b/drivers/scsi/3w-sas.c @@ -1328,7 +1328,7 @@ static int twl_reset_sequence(TW_Device_Extension *tw_dev, int soft_reset) } /* Load rest of compatibility struct */ - strncpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION, strlen(TW_DRIVER_VERSION)); + strcpy(tw_dev->tw_compat_info.driver_version, TW_DRIVER_VERSION); tw_dev->tw_compat_info.driver_srl_high = TW_CURRENT_DRIVER_SRL; tw_dev->tw_compat_info.driver_branch_high = TW_CURRENT_DRIVER_BRANCH; tw_dev->tw_compat_info.driver_build_high = TW_CURRENT_DRIVER_BUILD;
strncpy(dest, src, strlen(src)) leads to unterminated dest, which is dangerous. Here driver_version's len is 32 and TW_DRIVER_VERSION is shorter than 32. Therefore strcpy is OK. Signed-off-by: Chuhong Yuan <hslester96@gmail.com> --- drivers/scsi/3w-sas.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)