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From: "nsz at gcc dot gnu.org" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug dynamic-link/26926] New: aarch64: library dependencies are not
 bti protected
Date: Fri, 20 Nov 2020 11:28:35 +0000
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X-Bugzilla-Version: 2.32
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D26926

            Bug ID: 26926
           Summary: aarch64: library dependencies are not bti protected
           Product: glibc
           Version: 2.32
            Status: NEW
          Severity: normal
          Priority: P2
         Component: dynamic-link
          Assignee: unassigned at sourceware dot org
          Reporter: nsz at gcc dot gnu.org
  Target Milestone: ---

dl_open_check is only called on dlopened libraries not on
theirs dependencies, same for rtld_main_check: dependencies
are not checked.

the aarch64 backend *_check adds bti protection but it only
considers the passed linkmap, not its dependencies, so bti
protection is missing on those.

the bt VmFlag in /proc/self/smaps indicates bti protection, on
a bti enabled system it should be on all exec pages, but i see:

cat /proc/self/smaps |grep -E '(r-xp|VmFlags.*ex)'
00400000-004ff000 r-xp 00000000 00:14 10783380=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
/bin/busybox
VmFlags: rd ex mr mw me dw bt
fffff7d80000-fffff7edf000 r-xp 00000000 00:14 10759514=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20
/lib64/libc-2.32.9000.so
VmFlags: rd ex mr mw me
fffff7ef7000-fffff7f0a000 r-xp 00000000 00:14 10759538=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20
/lib64/libresolv-2.32.9000.so
VmFlags: rd ex mr mw me
fffff7f1e000-fffff7fb9000 r-xp 00000000 00:14 10759520=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20
/lib64/libm-2.32.9000.so
VmFlags: rd ex mr mw me
fffff7fca000-fffff7fed000 r-xp 00000000 00:14 10759508=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20
/lib64/ld-2.32.9000.so
VmFlags: rd ex mr mw me dw bt
fffff7ffc000-fffff7ffd000 r-xp 00000000 00:00 0                          [v=
dso]
VmFlags: rd ex mr mw me de bt

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