Bug 2211666

Summary: Ignore TERMINFO and HOME environment variables under root
Product: Red Hat Enterprise Linux 9 Reporter: Miroslav Lichvar <mlichvar>
Component: ncursesAssignee: Miroslav Lichvar <mlichvar>
Status: ON_QA --- QA Contact: Ondrej Mejzlik <omejzlik>
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Version: 9.1CC: omejzlik
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Fixed In Version: ncurses-6.2-9.20210508.el9 Doc Type: If docs needed, set a value
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Description Miroslav Lichvar 2023-06-01 11:46:02 UTC 
Description of problem:
ncurses uses the TERMINFO and HOME environment variables to search for terminfo entries. If there is a bug in parsing or handling (e.g. CVE-2023-29491), it can be exploited for setuid applications.

ncurses has configure option --disable-root-environ to not use there variables when running as root.

Consider building ncurses with this option to avoid this class of security issues.

How reproducible:
always

Steps to Reproduce:
1. TERMINFO="/tmp/terminfo" strace bash -i -c true |& grep terminfo

Actual results:
stat("/tmp/terminfo", 0x55b8e99c2900)   = -1 ENOENT (No such file or directory)
stat("/root/.terminfo", 0x55b8e99c2900) = -1 ENOENT (No such file or directory)
stat("/etc/terminfo", {st_mode=S_IFDIR|0755, st_size=6, ...}) = 0
stat("/usr/share/terminfo", {st_mode=S_IFDIR|0755, st_size=195, ...}) = 0
access("/etc/terminfo/s/screen", R_OK)  = -1 ENOENT (No such file or directory)
access("/usr/share/terminfo/s/screen", R_OK) = 0
openat(AT_FDCWD, "/usr/share/terminfo/s/screen", O_RDONLY) = 3


Expected results:
No access to /tmp/terminfo and /root/.terminfo is observed

Additional info: