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Groups > linux.kernel > #1258787
| From | Stephen Smalley <sds@tycho.nsa.gov> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] lkdtm: fix ACCESS_USERSPACE test |
| Date | 2015-10-29 14:30 +0100 |
| Message-ID | <qoVrc-Hx-19@gated-at.bofh.it> (permalink) |
| References | <qojlT-1pk-3@gated-at.bofh.it> <qomD8-3DG-21@gated-at.bofh.it> |
| Organization | National Security Agency |
On 10/27/2015 08:12 PM, Greg KH wrote: > On Tue, Oct 27, 2015 at 04:47:53PM -0400, Stephen Smalley wrote: >> Add a copy_to_user() call to the ACCESS_USERSPACE test >> prior to attempting direct dereferencing of the user >> address to ensure the page is present. Otherwise, >> a fault occurs on arm kernels even prior to the introduction >> of CONFIG_CPU_SW_DOMAIN_PAN, and there is no difference in >> behavior for CONFIG_CPU_SW_DOMAIN_PAN=n vs CONFIG_CPU_SW_DOMAIN_PAN=y. >> >> Before this change, for any value of CONFIG_CPU_SW_DOMAIN_PAN: >> lkdtm: Performing direct entry ACCESS_USERSPACE >> lkdtm: attempting bad read at b6fe8000 >> Unable to handle kernel paging request at virtual address b6fe8000 >> >> After this change, for CONFIG_CPU_SW_DOMAIN_PAN=n: >> lkdtm: Performing direct entry ACCESS_USERSPACE >> lkdtm: attempting bad read at b6efc000 >> lkdtm: attempting bad write at b6efc000 >> >> After this change, for CONFIG_CPU_SW_DOMAIN_PAN=y: >> lkdtm: Performing direct entry ACCESS_USERSPACE >> lkdtm: attempting bad read at b6f7d000 >> Unhandled fault: page domain fault (0x01b) at 0xb6f7d000 >> ... >> >> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> >> --- >> drivers/misc/lkdtm.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) > > Should this also be applied to older kernels (i.e. a stable fix)? I don't think it qualifies (only a fix for a kernel crash test), but will defer to Kees. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[PATCH] lkdtm: fix ACCESS_USERSPACE test Stephen Smalley <sds@tycho.nsa.gov> - 2015-10-27 21:50 +0100
Re: [PATCH] lkdtm: fix ACCESS_USERSPACE test Kees Cook <keescook@chromium.org> - 2015-10-27 22:30 +0100
Re: [PATCH] lkdtm: fix ACCESS_USERSPACE test Greg KH <gregkh@linuxfoundation.org> - 2015-10-28 01:20 +0100
Re: [PATCH] lkdtm: fix ACCESS_USERSPACE test Stephen Smalley <sds@tycho.nsa.gov> - 2015-10-29 14:30 +0100
Re: [PATCH] lkdtm: fix ACCESS_USERSPACE test Kees Cook <keescook@chromium.org> - 2015-10-30 19:10 +0100
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