Because cmd in struct spppreq (/usr/include/net/if_sppp.h) is an int, fuword32() should be used instead of fuword() in sys/net/if_spppsubr.c, line 5133, I think. Fix: Apply the patch I've appended. Or change the type of cmd in struct spppreq to unsigned long. Patch attached with submission follows: How-To-Repeat: Use /sbin/spppcontrol on a 64bit machine.
---------- Forwarded message ---------- From: Jens Wiatrowski <wiatro@gmx.net> Date: 23 October 2012 16:40 Subject: Re: Re: kern/173002: data type size problem in if_spppsubr.c To: Eitan Adler <lists@eitanadler.com> Hello Eitan, > >please send the output of "diff -u" (unified diff) - this makes it >more likely someone will look at the patch > Attached. Regards Jens -- Eitan Adler
Responsible Changed From-To: freebsd-bugs->freebsd-net Over to maintainer(s).
For bugs matching the following criteria: Status: In Progress Changed: (is less than) 2014-06-01 Reset to default assignee and clear in-progress tags. Mail being skipped
I have no clue which type is right here; return PR to the net@
Actually user space `struct spppreq spr` is not explicitly zeroed [1], so `fuword() / fueword()` can read garbage into kernel space. I guess /sbin/spppcontrol will get error EINVAL occasionally on a 64bit platforms. As this is an old report, not sure if the reporter Jens can confirm this. 1. https://cgit.freebsd.org/src/tree/sbin/spppcontrol/spppcontrol.c?h=stable/13#n63
(In reply to Zhenlei Huang from comment #5) Proposed fix https://reviews.freebsd.org/D47335 .
A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=08ec14fecf6a93c0321c31ba1f0b04db6b888f16 commit 08ec14fecf6a93c0321c31ba1f0b04db6b888f16 Author: Zhenlei Huang <zlei@FreeBSD.org> AuthorDate: 2025-01-14 10:56:49 +0000 Commit: Zhenlei Huang <zlei@FreeBSD.org> CommitDate: 2025-01-14 10:56:49 +0000 sppp: Fix getting wrong spppreq cmd from ioctl ifr->ifr_data is supposed to point to a struct spppreq. The first member cmd of struct spppreq is int type. It was pre-read via `fueword()` before a full fetching. Unfortunately an user space `struct spppreq spr` may not be zeroed explicitly, on 64bit architectures `fueword()` reads 64bit word thus the garbage (extra 4 bytes) may be read into kernel space (subcmd). Prior to f9d8181868ee, `subcmd` was declared as int and assigned from `fuword()` and was implicitly converted from long to int. On 64bit little endian architectures the implicitly conversion overflows (undefined bahavior) which happen to trash the garbage (the extra 4 bytes, high 32 bits) and worked, but no luck on 64bit big endian architectures. Since f9d8181868ee `subcmd` was changed to u_long then there is no conversion so we end up mismatching `subcmd` with user space's `cmd`. It is also a bit hackish to get the value of cmd via `fueword()`, instead we refer to it directly from spr->cmd. This is a direct commit to stable/13 as sppp(4) no longer exists in main and stable/14. PR: 173002 Reviewed by: glebius (previous version) Fixes: f9d8181868ee Fixed yet more ioctl breakage due to the type of ... Differential Revision: https://reviews.freebsd.org/D47335 sys/net/if_spppsubr.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-)
Fixed in stable/13.