On Sat, Dec 06, 2014 at 06:13:08PM +0100, Willy Tarreau wrote:
> Hi Luis,
>
> On Fri, Dec 05, 2014 at 03:21:01PM +0000, Luis Henriques wrote:
> > Your backport of commit 6f442be2fb22 ("x86_64, traps: Stop using IST
> > for #SS") seems to be identical to mine, but I'm unable to confirm
> > that it is sufficient to fix the security issue.
>
> If that can help, I just found that this public test code from Andy
> is sufficient to test the backports :
>
> https://gitorious.org/linux-test-utils/linux-clock-tests/raw/sigreturn.c
>
Thank you for pointing me at this. I'll see if I can reproduce with a
Lucid kernel and test the backports.
Cheers,
--
Luís
> On a plain 2.6.32.64 (x86_64), running the code above built with -m32
> kills the kernel, probably from a triple fault since I'm not seeing
> any panic message and it immediately reboots :
>
> $ /tmp/sigreturn
> [RUN]
> => reboot
>
> On the patched kernel :
>
> $ /tmp/sigreturn
> [RUN] 64-bit CS (33), 32-bit SS (2b)
> SP: 5aadc0de -> 5aadc0de
> [OK] all registers okay
> [RUN] 32-bit CS (23), 32-bit SS (2b)
> SP: 5aadc0de -> 5aadc0de
> [OK] all registers okay
> [RUN] 16-bit CS (7), 32-bit SS (2b)
> SP: 5aadc0de -> 5aadc0de
> [OK] all registers okay
> [RUN] 64-bit CS (33), 16-bit SS (f)
> SP: 5aadc0de -> 5aadc0de
> [OK] all registers okay
> [RUN] 32-bit CS (23), 16-bit SS (f)
> SP: 5aadc0de -> 5aadc0de
> [OK] all registers okay
> [RUN] 16-bit CS (7), 16-bit SS (f)
> SP: 5aadc0de -> 5aadc0de
> [OK] all registers okay
> [RUN] 64-bit CS (33), bogus SS (17)
> [OK] Got #GP(0x0) (i.e. Segmentation fault)
> [RUN] 32-bit CS (23), bogus SS (17)
> [OK] Got #GP(0x0) (i.e. Segmentation fault)
> [RUN] 16-bit CS (7), bogus SS (17)
> [OK] Got #GP(0x0) (i.e. Segmentation fault)
> [RUN] 64-bit CS (33), bogus SS (23)
> [OK] Got #GP(0x20) (i.e. GDT index 4, Segmentation fault)
> [RUN] 32-bit CS (23), bogus SS (23)
> [OK] Got #GP(0x20) (i.e. GDT index 4, Segmentation fault)
> [RUN] 16-bit CS (7), bogus SS (23)
> [OK] Got #GP(0x20) (i.e. GDT index 4, Segmentation fault)
> [RUN] 32-bit CS (1f), bogus SS (2b)
> [OK] Got #NP(0x1c) (i.e. LDT index 3, Bus error)
> [RUN] 32-bit CS (23), bogus SS (27)
> [OK] Got #GP(0x0) (i.e. Segmentation fault)
> $
>
> Hoping this helps. BTW, I'm about to issue -rc1 which includes the
> last series of patches as well as the other CVE fixes that you and
> Moritz sent me.
>
> Best regards,
> Willy
>
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