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Signed-off-by: Aizal Khan <aizumusheer2@gmail.com> (cherry picked from commit 17d6795) Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>
cf-agent reconstructs the absolute target of a relative symbolic link by appending the readlink() result onto the link's directory name in a CF_BUFSIZE stack buffer. KillGhostLink() in files_links.c did this with an unbounded strcat(linkpath, linkbuf), and LinkCopy() in verify_files_utils.c with strncat(vbuff, linkbuf, CF_BUFSIZE - 1), whose third argument is the maximum number of bytes to take from the source, not the space left in the destination. readlink() returns up to CF_BUFSIZE - 1 bytes, so a symlink whose relative target is near CF_BUFSIZE, left by an unprivileged user in a directory that a root files promise walks (depth_search, perms, link copy), overflows the stack of the agent. KillGhostLink() runs on every symlink met during a recursive descent, before the dead-link stat(). Bound both appends with strlcat(..., sizeof(buf)), the same way ExpandLinks() in files_links.c already does. KillGhostLink() bails out with an "Internal limit reached" message and LinkCopy() fails the promise when the target does not fit, rather than truncating it into a link pointing somewhere else. Normal links are unchanged. The regression test is skipped when symlink() rejects the long target with ENAMETOOLONG, as macOS does. Changelog: Title Signed-off-by: Dhanraj E <dhanraj@labs.digiscrypt.com> (cherry picked from commit dac3db2) Signed-off-by: Lars Erik Wik <lars.erik.wik@northern.tech>
This was referenced Nov 6, 2026
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Thank you for submitting a pull request! Maybe @craigcomstock can review this? |
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@cf-bottom Jenkins with exotics please :) |
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Alright, I triggered a build: (with exotics) Jenkins: https://ci.cfengine.com/job/pr-pipeline/15024/ Packages: http://buildcache.cfengine.com/packages/testing-pr/jenkins-pr-pipeline-15024/ |
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Backport of #6209 and #6425.
#6209 is included because #6425 extends the unit test it adds.
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