From: Sean Christopherson Date: Fri, 13 Mar 2026 17:48:53 +0000 (-0700) Subject: crypto: ccp: Don't attempt to copy PDH cert to userspace if PSP command failed X-Git-Tag: v7.1-rc1~61^2~5 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=e76239fed3cffd6d304d8ca3ce23984fd24f57d3;p=thirdparty%2Flinux.git crypto: ccp: Don't attempt to copy PDH cert to userspace if PSP command failed When retrieving the PDH cert, don't attempt to copy the blobs to userspace if the firmware command failed. If the failure was due to an invalid length, i.e. the userspace buffer+length was too small, copying the number of bytes _firmware_ requires will overflow the kernel-allocated buffer and leak data to userspace. BUG: KASAN: slab-out-of-bounds in instrument_copy_to_user ../include/linux/instrumented.h:129 [inline] BUG: KASAN: slab-out-of-bounds in _inline_copy_to_user ../include/linux/uaccess.h:205 [inline] BUG: KASAN: slab-out-of-bounds in _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26 Read of size 2084 at addr ffff8885c4ab8aa0 by task syz.0.186/21033 CPU: 51 UID: 0 PID: 21033 Comm: syz.0.186 Tainted: G U O 7.0.0-smp-DEV #28 PREEMPTLAZY Tainted: [U]=USER, [O]=OOT_MODULE Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.84.12-0 11/17/2025 Call Trace: dump_stack_lvl+0xc5/0x110 ../lib/dump_stack.c:120 print_address_description ../mm/kasan/report.c:378 [inline] print_report+0xbc/0x260 ../mm/kasan/report.c:482 kasan_report+0xa2/0xe0 ../mm/kasan/report.c:595 check_region_inline ../mm/kasan/generic.c:-1 [inline] kasan_check_range+0x264/0x2c0 ../mm/kasan/generic.c:200 instrument_copy_to_user ../include/linux/instrumented.h:129 [inline] _inline_copy_to_user ../include/linux/uaccess.h:205 [inline] _copy_to_user+0x66/0xa0 ../lib/usercopy.c:26 copy_to_user ../include/linux/uaccess.h:236 [inline] sev_ioctl_do_pdh_export+0x3d3/0x7c0 ../drivers/crypto/ccp/sev-dev.c:2347 sev_ioctl+0x2a2/0x490 ../drivers/crypto/ccp/sev-dev.c:2568 vfs_ioctl ../fs/ioctl.c:51 [inline] __do_sys_ioctl ../fs/ioctl.c:597 [inline] __se_sys_ioctl+0x11d/0x1b0 ../fs/ioctl.c:583 do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe0/0x800 ../arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e WARN if the driver says the command succeeded, but the firmware error code says otherwise, as __sev_do_cmd_locked() is expected to return -EIO on any firwmware error. Reported-by: Alexander Potapenko Reported-by: Sebastian Alba Vives Fixes: 76a2b524a4b1 ("crypto: ccp: Implement SEV_PDH_CERT_EXPORT ioctl command") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Signed-off-by: Herbert Xu --- diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index 86c6858a5c18..e4c7c2a6fe55 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -2339,7 +2339,10 @@ cmd: ret = __sev_do_cmd_locked(SEV_CMD_PDH_CERT_EXPORT, &data, &argp->error); - /* If we query the length, FW responded with expected data. */ + /* + * Firmware will return the length of the blobs (either the minimum + * required length or the actual length written), return 'em to the user. + */ input.cert_chain_len = data.cert_chain_len; input.pdh_cert_len = data.pdh_cert_len; @@ -2348,6 +2351,9 @@ cmd: goto e_free_cert; } + if (ret || WARN_ON_ONCE(argp->error)) + goto e_free_cert; + if (pdh_blob) { if (copy_to_user(input_pdh_cert_address, pdh_blob, input.pdh_cert_len)) {