[Bug libc/31695] New: pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[Bug libc/31695] New: pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[corsix at corsix dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

            Bug ID: 31695
           Summary: pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds
                    but execve fails
           Product: glibc
           Version: 2.39
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: corsix at corsix dot org
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---

Created attachment 15483
  --> https://sourceware.org/bugzilla/attachment.cgi?id=15483&action=edit
test.c

The pidfd_spawn / pidfd_spawnp functions introduced as part of BZ#30349 will
allocate an fd as part of the clone3 call, but only return that fd to their
caller if the execve in the child succeeds. If the execve in the child fails,
then pidfd_spawn / pidfd_spawnp will reap the child and return an appropriate
error code to their caller. This error handling path currently forgets to close
the fd, resulting in an fd leak.

Trivial test program attached that makes a number of pidfd_spawnp calls, prints
the returned error code and returned pidfd, and then lists the contents of
/proc/self/fd. The returned error code is correct (ENOENT), and no pidfd is
returned, but then the listing step reports a bunch of leaked pidfds floating
around.

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[Bug libc/31695] pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com

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[Bug libc/31695] pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security?

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[Bug libc/31695] pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2024-05-03
             Status|UNCONFIRMED                 |NEW

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[Bug libc/31695] pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sam at gentoo dot org

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[Bug libc/31695] pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[adhemerval.zanella at linaro dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at sourceware dot org   |adhemerval.zanella at linaro dot o
                   |                            |rg
             Status|NEW                         |ASSIGNED
                 CC|                            |adhemerval.zanella at linaro dot o
                   |                            |rg

--- Comment #1 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
I am working a patch to fix it, thanks to bring this up.

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[Bug libc/31695] pidfd_spawn/pidfd_spawnp leak an fd if clone3 succeeds but execve fails

[adhemerval.zanella at linaro dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31695

Adhemerval Zanella <adhemerval.zanella at linaro dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |2.40
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #2 from Adhemerval Zanella <adhemerval.zanella at linaro dot org> ---
Fixed on 2.40.

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