Messages in this thread | | | Date | Fri, 5 Apr 2024 23:28:20 +0900 | Subject | Re: [syzbot] [hardening?] [mm?] BUG: bad usercopy in fpa_set | From | Tetsuo Handa <> |
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On 2024/04/04 1:12, Russell King (Oracle) wrote: > Therefore, there is _no way_ for fpa_set() to overwrite anything > outside of thread_info->fpstate, because sizeof(struct user_fp) > is smaller than sizeof(thread->fpstate). > > Syzbot appears to be wrong in this instance. >
Thanks for clarification.
I came to suspect that commit 08626a6056aa ("arm: Implement thread_struct whitelist for hardened usercopy") missed that ptrace(PTRACE_SETFPREGS) needs to declare a usercopy whitelist. It seems to me that https://syzkaller.appspot.com/text?tag=Patch&x=14c42099180000 can fix this problem, but I'm not sure whether this is safe/correct. Can you check?
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