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Groups > linux.kernel > #1671080 > unrolled thread
| Started by | Kees Cook <keescook@chromium.org> |
|---|---|
| First post | 2017-06-20 22:30 +0200 |
| Last post | 2017-06-28 20:00 +0200 |
| Articles | 2 — 1 participant |
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Re: [PATCH v10 1/3] x86/syscalls: Check address limit on user-mode return Kees Cook <keescook@chromium.org> - 2017-06-20 22:30 +0200
Re: [PATCH v10 1/3] x86/syscalls: Check address limit on user-mode return Kees Cook <keescook@chromium.org> - 2017-06-28 20:00 +0200
| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Date | 2017-06-20 22:30 +0200 |
| Subject | Re: [PATCH v10 1/3] x86/syscalls: Check address limit on user-mode return |
| Message-ID | <tUxWG-4Sn-7@gated-at.bofh.it> |
On Wed, Jun 14, 2017 at 6:12 PM, Thomas Garnier <thgarnie@google.com> wrote: > Ensure the address limit is a user-mode segment before returning to > user-mode. Otherwise a process can corrupt kernel-mode memory and elevate > privileges [1]. > > The set_fs function sets the TIF_SETFS flag to force a slow path on > return. In the slow path, the address limit is checked to be USER_DS if > needed. > > The addr_limit_user_check function is added as a cross-architecture > function to check the address limit. > > [1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990 > > Signed-off-by: Thomas Garnier <thgarnie@google.com> Thanks for reworking this series! The bad state correctly BUGs under the LKDTM test: [ 21.171586] lkdtm: Performing direct entry CORRUPT_USER_DS [ 21.172791] lkdtm: setting bad task size limit [ 21.173742] ------------[ cut here ]------------ [ 21.174641] kernel BUG at ./include/linux/syscalls.h:220! ... [ 21.193166] Call Trace: [ 21.193617] ? trace_hardirqs_on_thunk+0x1a/0x1c [ 21.194443] entry_SYSCALL64_slow_path+0x25/0x25 Tested-by: Kees Cook <keescook@chromium.org> -Kees -- Kees Cook Pixel Security
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| From | Kees Cook <keescook@chromium.org> |
|---|---|
| Date | 2017-06-28 20:00 +0200 |
| Message-ID | <tXpq1-t5-145@gated-at.bofh.it> |
| In reply to | #1671080 |
On Tue, Jun 20, 2017 at 1:24 PM, Kees Cook <keescook@chromium.org> wrote: > On Wed, Jun 14, 2017 at 6:12 PM, Thomas Garnier <thgarnie@google.com> wrote: >> Ensure the address limit is a user-mode segment before returning to >> user-mode. Otherwise a process can corrupt kernel-mode memory and elevate >> privileges [1]. >> >> The set_fs function sets the TIF_SETFS flag to force a slow path on >> return. In the slow path, the address limit is checked to be USER_DS if >> needed. >> >> The addr_limit_user_check function is added as a cross-architecture >> function to check the address limit. >> >> [1] https://bugs.chromium.org/p/project-zero/issues/detail?id=990 >> >> Signed-off-by: Thomas Garnier <thgarnie@google.com> > > Thanks for reworking this series! > > The bad state correctly BUGs under the LKDTM test: > > [ 21.171586] lkdtm: Performing direct entry CORRUPT_USER_DS > [ 21.172791] lkdtm: setting bad task size limit > [ 21.173742] ------------[ cut here ]------------ > [ 21.174641] kernel BUG at ./include/linux/syscalls.h:220! > ... > [ 21.193166] Call Trace: > [ 21.193617] ? trace_hardirqs_on_thunk+0x1a/0x1c > [ 21.194443] entry_SYSCALL64_slow_path+0x25/0x25 > > > Tested-by: Kees Cook <keescook@chromium.org> Is everyone happy with this patch for x86? Does this need anything more/different? Thanks! -Kees -- Kees Cook Pixel Security
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