CVE-2018-15854

Unchecked NULL pointer usage in xkbcommon before 0.8.1 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because geometry tokens were desupported incorrectly.

Updated libxkbcommon packages fix security vulnerabilities:

Endless recursion exists in xkbcomp/expr.c in xkbcommon and libxkbcommon before 0.8.1, which could be used by local attackers to crash xkbcommon users by supplying a crafted keymap file that triggers boolean negation (CVE-2018-15853).

Unchecked NULL pointer usage in xkbcommon before 0.8.1 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because geometry tokens were desupported incorrectly (CVE-2018-15854).

Unchecked NULL pointer usage in xkbcommon before 0.8.1 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because the XkbFile for an xkb_geometry section was mishandled (CVE-2018-15855).

An infinite loop when reaching EOL unexpectedly in compose/parser.c (aka the keymap parser) in xkbcommon before 0.8.1 could be used by local attackers to cause a denial of service during parsing of crafted keymap files (CVE-2018-15856).

An invalid free in ExprAppendMultiKeysymList in xkbcomp/ast-build.c in xkbcommon before 0.8.1 could be used by local attackers to crash xkbcommon keymap parsers or possibly have unspecified other impact by supplying a crafted keymap file (CVE-2018-15857).

Unchecked NULL pointer usage when handling invalid aliases in CopyKeyAliasesToKeymap in xkbcomp/keycodes.c in xkbcommon before 0.8.1 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file (CVE-2018-15858).

Unchecked NULL pointer usage when parsing invalid atoms in ExprResolveLhs in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because lookup failures are mishandled (CVE-2018-15859).

Unchecked NULL pointer usage in ExprResolveLhs in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file that triggers an xkb_intern_atom failure (CVE-2018-15861).

Unchecked NULL pointer usage in LookupModMask in xkbcomp/expr.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file with invalid virtual modifiers (CVE-2018-15862).

Unchecked NULL pointer usage in ResolveStateAndPredicate in xkbcomp/compat.c in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file with a no-op modmask expression (CVE-2018-15863).

Unchecked NULL pointer usage in resolve_keysym in xkbcomp/parser.y in xkbcommon before 0.8.2 could be used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because a map access attempt can occur for a map that was never created (CVE-2018-15864).

This update for libxkbcommon to version 0.8.2 fixes the following issues:

• Fix a few NULL-dereferences, out-of-bounds access and undefined behavior in the XKB text format parser.
• CVE-2018-15853: Endless recursion could have been used by local attackers to crash xkbcommon users by supplying a crafted keymap file that triggers boolean negation (bsc#1105832).
• CVE-2018-15854: Unchecked NULL pointer usage could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because geometry tokens were desupported incorrectly (bsc#1105832).
• CVE-2018-15855: Unchecked NULL pointer usage could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because the XkbFile for an xkb_geometry section was mishandled (bsc#1105832).
• CVE-2018-15856: An infinite loop when reaching EOL unexpectedly could be used by local attackers to cause a denial of service during parsing of crafted keymap files (bsc#1105832).
• CVE-2018-15857: An invalid free in ExprAppendMultiKeysymList could have been used by local attackers to crash xkbcommon keymap parsers or possibly have unspecified other impact by supplying a crafted keymap file (bsc#1105832).
• CVE-2018-15858: Unchecked NULL pointer usage when handling invalid aliases in CopyKeyAliasesToKeymap could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file (bsc#1105832).
• CVE-2018-15859: Unchecked NULL pointer usage when parsing invalid atoms in ExprResolveLhs could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because lookup failures are mishandled (bsc#1105832).
• CVE-2018-15861: Unchecked NULL pointer usage in ExprResolveLhs could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file that triggers an xkb_intern_atom failure (bsc#1105832).
• CVE-2018-15862: Unchecked NULL pointer usage in LookupModMask could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file with invalid virtual modifiers (bsc#1105832).
• CVE-2018-15863: Unchecked NULL pointer usage in ResolveStateAndPredicate could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file with a no-op modmask expression (bsc#1105832).
• CVE-2018-15864: Unchecked NULL pointer usage in resolve_keysym could have been used by local attackers to crash (NULL pointer dereference) the xkbcommon parser by supplying a crafted keymap file, because a map access attempt can occur for a map that was never created (bsc#1105832).

This update for libxkbcommon fixes the following issues:

Fixed multiple memory handling and correctness issues (bsc#1105832):

• CVE-2018-15859
• CVE-2018-15856
• CVE-2018-15858
• CVE-2018-15864
• CVE-2018-15863
• CVE-2018-15862
• CVE-2018-15861
• CVE-2018-15855
• CVE-2018-15854
• CVE-2018-15857
• CVE-2018-15853

It was discovered that libxkbcommon incorrectly handled certain files. An attacker could possibly use this issue to cause a denial of service. (CVE-2018-15853, CVE-2018-15854, CVE-2018-15855, CVE-2018-15856, CVE-2018-15857, CVE-2018-15858, CVE-2018-15859, CVE-2018-15861, CVE-2018-15862, CVE-2018-15863, CVE-2018-15864)

USN-3786-1 fixed several vulnerabilities in libxkbcommon. This update provides the corresponding update for Ubuntu 18.04 LTS.

Original advisory details:

It was discovered that libxkbcommon incorrectly handled certain files. An attacker could possibly use this issue to cause a denial of service. (CVE-2018-15853, CVE-2018-15854, CVE-2018-15855, CVE-2018-15856, CVE-2018-15857, CVE-2018-15858, CVE-2018-15859, CVE-2018-15861, CVE-2018-15862, CVE-2018-15863, CVE-2018-15864)