The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 7024f60d655272bd2ca1d3a4c9e0a63319b1eea1 Gitweb: https://git.kernel.org/tip/7024f60d655272bd2ca1d3a4c9e0a63319b1eea1 Author: Hyunwook (Wooky) Baek <baekhw@xxxxxxxxxx> AuthorDate: Sat, 09 Jan 2021 23:11:02 -08:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Mon, 11 Jan 2021 20:01:52 +01:00 x86/sev-es: Handle string port IO to kernel memory properly Don't assume dest/source buffers are userspace addresses when manually copying data for string I/O or MOVS MMIO, as {get,put}_user() will fail if handed a kernel address and ultimately lead to a kernel panic. When invoking INSB/OUTSB instructions in kernel space in a SEV-ES-enabled VM, the kernel crashes with the following message: "SEV-ES: Unsupported exception in #VC instruction emulation - can't continue" Handle that case properly. [ bp: Massage commit message. ] Fixes: f980f9c31a92 ("x86/sev-es: Compile early handler code into kernel image") Signed-off-by: Hyunwook (Wooky) Baek <baekhw@xxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20210110071102.2576186-1-baekhw@xxxxxxxxxx --- arch/x86/kernel/sev-es.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 0bd1a0f..ab31c34 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -286,6 +286,12 @@ static enum es_result vc_write_mem(struct es_em_ctxt *ctxt, u16 d2; u8 d1; + /* If instruction ran in kernel mode and the I/O buffer is in kernel space */ + if (!user_mode(ctxt->regs) && !access_ok(target, size)) { + memcpy(dst, buf, size); + return ES_OK; + } + switch (size) { case 1: memcpy(&d1, buf, 1); @@ -335,6 +341,12 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, u16 d2; u8 d1; + /* If instruction ran in kernel mode and the I/O buffer is in kernel space */ + if (!user_mode(ctxt->regs) && !access_ok(s, size)) { + memcpy(buf, src, size); + return ES_OK; + } + switch (size) { case 1: if (get_user(d1, s))
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