(release/25.1) xkb: Fix bounds check in _CheckSetGeom()#2261
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metux merged 1 commit intorelease/25.1from Apr 21, 2026
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As reported by valgrind: == Conditional jump or move depends on uninitialised value(s) == at 0x5CBE66: SrvXkbAddGeomKeyAlias (XKBGAlloc.c:585) == by 0x5AC7D5: _CheckSetGeom (xkb.c:5607) == by 0x5AC952: _XkbSetGeometry (xkb.c:5643) == by 0x5ACB58: ProcXkbSetGeometry (xkb.c:5684) == by 0x5B0DAC: ProcXkbDispatch (xkb.c:7070) == by 0x4A28C5: Dispatch (dispatch.c:553) == by 0x4B0B24: dix_main (main.c:274) == by 0x42915E: main (stubmain.c:34) == Uninitialised value was created by a heap allocation == at 0x4840B26: malloc (vg_replace_malloc.c:447) == by 0x5E13B0: AllocateInputBuffer (io.c:981) == by 0x5E05CD: InsertFakeRequest (io.c:516) == by 0x4AA860: NextAvailableClient (dispatch.c:3629) == by 0x5DE0D7: AllocNewConnection (connection.c:628) == by 0x5DE2C6: EstablishNewConnections (connection.c:692) == by 0x5DE600: HandleNotifyFd (connection.c:809) == by 0x5E2598: ospoll_wait (ospoll.c:660) == by 0x5DA00C: WaitForSomething (WaitFor.c:208) == by 0x4A26E5: Dispatch (dispatch.c:493) == by 0x4B0B24: dix_main (main.c:274) == by 0x42915E: main (stubmain.c:34) Each key alias entry contains two key names (the alias and the real key name), each of size XkbKeyNameLength. The current bounds check only validates the first name, allowing XkbAddGeomKeyAlias to potentially read uninitialized memory when accessing the second name at &wire[XkbKeyNameLength]. To fix this, change the value to check to use 2 * XkbKeyNameLength to validate the bounds. CVE-2026-34000, ZDI-CAN-28679 This vulnerability was discovered by: Jan-Niklas Sohn working with TrendAI Zero Day Initiative Signed-off-by: Olivier Fourdan <ofourdan@redhat.com> Acked-by: Peter Hutterer <peter.hutterer@who-t.net> Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2176>
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As reported by valgrind:
== Conditional jump or move depends on uninitialised value(s)
== at 0x5CBE66: SrvXkbAddGeomKeyAlias (XKBGAlloc.c:585)
== by 0x5AC7D5: _CheckSetGeom (xkb.c:5607)
== by 0x5AC952: _XkbSetGeometry (xkb.c:5643)
== by 0x5ACB58: ProcXkbSetGeometry (xkb.c:5684)
== by 0x5B0DAC: ProcXkbDispatch (xkb.c:7070)
== by 0x4A28C5: Dispatch (dispatch.c:553)
== by 0x4B0B24: dix_main (main.c:274)
== by 0x42915E: main (stubmain.c:34)
== Uninitialised value was created by a heap allocation
== at 0x4840B26: malloc (vg_replace_malloc.c:447)
== by 0x5E13B0: AllocateInputBuffer (io.c:981)
== by 0x5E05CD: InsertFakeRequest (io.c:516)
== by 0x4AA860: NextAvailableClient (dispatch.c:3629)
== by 0x5DE0D7: AllocNewConnection (connection.c:628)
== by 0x5DE2C6: EstablishNewConnections (connection.c:692)
== by 0x5DE600: HandleNotifyFd (connection.c:809)
== by 0x5E2598: ospoll_wait (ospoll.c:660)
== by 0x5DA00C: WaitForSomething (WaitFor.c:208)
== by 0x4A26E5: Dispatch (dispatch.c:493)
== by 0x4B0B24: dix_main (main.c:274)
== by 0x42915E: main (stubmain.c:34)
Each key alias entry contains two key names (the alias and the real key
name), each of size XkbKeyNameLength.
The current bounds check only validates the first name, allowing
XkbAddGeomKeyAlias to potentially read uninitialized memory when
accessing the second name at &wire[XkbKeyNameLength].
To fix this, change the value to check to use 2 * XkbKeyNameLength to
validate the bounds.
CVE-2026-34000, ZDI-CAN-28679
This vulnerability was discovered by:
Jan-Niklas Sohn working with TrendAI Zero Day Initiative
Signed-off-by: Olivier Fourdan ofourdan@redhat.com
Acked-by: Peter Hutterer peter.hutterer@who-t.net
Part-of: https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2176