diff options
| author | Joerg Roedel | 2023-10-16 14:42:50 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2023-10-25 12:03:04 +0200 |
| commit | 57d0639f60f1ff04cbe7fd52823b94b894d7f812 (patch) | |
| tree | 8b47d78c7df883efb11c46a27e6b53d8e9192537 /arch/x86/kernel | |
| parent | def94eb9a804acdcdba5b959ad72cf9119f03f3b (diff) | |
x86/sev: Check for user-space IOIO pointing to kernel space
Upstream commit: 63e44bc52047f182601e7817da969a105aa1f721
Check the memory operand of INS/OUTS before emulating the instruction.
The #VC exception can get raised from user-space, but the memory operand
can be manipulated to access kernel memory before the emulation actually
begins and after the exception handler has run.
[ bp: Massage commit message. ]
Fixes: 597cfe48212a ("x86/boot/compressed/64: Setup a GHCB-based VC Exception handler")
Reported-by: Tom Dohrmann <erbse.13@gmx.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/sev-shared.c | 31 |
1 files changed, 29 insertions, 2 deletions
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index abbe7af14d92..71d8698702ce 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -629,6 +629,23 @@ fail: sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); } +static enum es_result vc_insn_string_check(struct es_em_ctxt *ctxt, + unsigned long address, + bool write) +{ + if (user_mode(ctxt->regs) && fault_in_kernel_space(address)) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.error_code = X86_PF_USER; + ctxt->fi.cr2 = address; + if (write) + ctxt->fi.error_code |= X86_PF_WRITE; + + return ES_EXCEPTION; + } + + return ES_OK; +} + static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt, void *src, char *buf, unsigned int data_size, @@ -636,7 +653,12 @@ static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt, bool backwards) { int i, b = backwards ? -1 : 1; - enum es_result ret = ES_OK; + unsigned long address = (unsigned long)src; + enum es_result ret; + + ret = vc_insn_string_check(ctxt, address, false); + if (ret != ES_OK) + return ret; for (i = 0; i < count; i++) { void *s = src + (i * data_size * b); @@ -657,7 +679,12 @@ static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt, bool backwards) { int i, s = backwards ? -1 : 1; - enum es_result ret = ES_OK; + unsigned long address = (unsigned long)dst; + enum es_result ret; + + ret = vc_insn_string_check(ctxt, address, true); + if (ret != ES_OK) + return ret; for (i = 0; i < count; i++) { void *d = dst + (i * data_size * s); |