From: Benjamin Berg Date: Wed, 4 Jun 2025 08:17:05 +0000 (+0200) Subject: um: fix SECCOMP 32bit xstate register restore X-Git-Tag: v6.16-rc1~38^2~2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=942349413a49670e8bed246e2185fd3a053227be;p=thirdparty%2Fkernel%2Flinux.git um: fix SECCOMP 32bit xstate register restore There was a typo that caused the extended FP state to be copied into the wrong location on 32 bit. On 32 bit we only store the xstate internally as that already contains everything. However, for compatibility, the mcontext on 32 bit first contains the legacy FP state and then the xstate. The code copied the xstate on top of the legacy FP state instead of using the correct offset. This offset was already calculated in the xstate_* variables, so simply switch to those to fix the problem. With this SECCOMP mode works on 32 bit, so lift the restriction. Fixes: b1e1bd2e6943 ("um: Add helper functions to get/set state for SECCOMP") Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20250604081705.934112-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg --- diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index 49015be1aaaf4..a827c2e01aa53 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -296,10 +296,6 @@ static bool __init init_seccomp(void) int n; unsigned long sp; - /* doesn't work on 32-bit right now */ - if (!IS_ENABLED(CONFIG_64BIT)) - return false; - /* * We check that we can install a seccomp filter and then exit(0) * from a trapped syscall. diff --git a/arch/x86/um/os-Linux/mcontext.c b/arch/x86/um/os-Linux/mcontext.c index e661fdc44db93..a21403df66637 100644 --- a/arch/x86/um/os-Linux/mcontext.c +++ b/arch/x86/um/os-Linux/mcontext.c @@ -231,7 +231,7 @@ int set_stub_state(struct uml_pt_regs *regs, struct stub_data *data, xstate_size = fp_size; #endif - memcpy(fpstate_stub, ®s->fp, fp_size); + memcpy(xstate_stub, ®s->fp, xstate_size); #ifdef __i386__ /*