On Tue, Jun 20, 2017 at 1:24 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Wed, Jun 14, 2017 at 6:12 PM, Thomas Garnier <thgarnie@xxxxxxxxxx> 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@xxxxxxxxxx> > > 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@xxxxxxxxxxxx> Is everyone happy with this patch for x86? Does this need anything more/different? Thanks! -Kees -- Kees Cook Pixel Security -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
