This is a note to let you know that I've just added the patch titled virt/sev-guest: Return -EIO if certificate buffer is not large enough to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: virt-sev-guest-return-eio-if-certificate-buffer-is-not-large-enough.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From dd093fb08e8f8a958fec4eef36f9f09eac047f60 Mon Sep 17 00:00:00 2001 From: Tom Lendacky <thomas.lendacky@xxxxxxx> Date: Wed, 22 Feb 2023 10:39:39 -0600 Subject: virt/sev-guest: Return -EIO if certificate buffer is not large enough From: Tom Lendacky <thomas.lendacky@xxxxxxx> commit dd093fb08e8f8a958fec4eef36f9f09eac047f60 upstream. Commit 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") changed the behavior associated with the return value when the caller does not supply a large enough certificate buffer. Prior to the commit a value of -EIO was returned. Now, 0 is returned. This breaks the established ABI with the user. Change the code to detect the buffer size error and return -EIO. Fixes: 47894e0fa6a5 ("virt/sev-guest: Prevent IV reuse in the SNP guest driver") Reported-by: Larry Dewey <larry.dewey@xxxxxxx> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx> Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> Tested-by: Larry Dewey <larry.dewey@xxxxxxx> Cc: <stable@xxxxxxxxxx> Link: https://lore.kernel.org/r/2afbcae6daf13f7ad5a4296692e0a0fe1bc1e4ee.1677083979.git.thomas.lendacky@xxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/virt/coco/sev-guest/sev-guest.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -379,9 +379,26 @@ static int handle_guest_request(struct s snp_dev->input.data_npages = certs_npages; } + /* + * Increment the message sequence number. There is no harm in doing + * this now because decryption uses the value stored in the response + * structure and any failure will wipe the VMPCK, preventing further + * use anyway. + */ + snp_inc_msg_seqno(snp_dev); + if (fw_err) *fw_err = err; + /* + * If an extended guest request was issued and the supplied certificate + * buffer was not large enough, a standard guest request was issued to + * prevent IV reuse. If the standard request was successful, return -EIO + * back to the caller as would have originally been returned. + */ + if (!rc && err == SNP_GUEST_REQ_INVALID_LEN) + return -EIO; + if (rc) { dev_alert(snp_dev->dev, "Detected error from ASP request. rc: %d, fw_err: %llu\n", @@ -397,9 +414,6 @@ static int handle_guest_request(struct s goto disable_vmpck; } - /* Increment to new message sequence after payload decryption was successful. */ - snp_inc_msg_seqno(snp_dev); - return 0; disable_vmpck: Patches currently in stable-queue which might be from thomas.lendacky@xxxxxxx are queue-6.1/crypto-ccp-failure-on-re-initialization-due-to-dupli.patch queue-6.1/x86-virt-force-gif-1-prior-to-disabling-svm-for-reboot-flows.patch queue-6.1/crypto-ccp-avoid-page-allocation-failure-warning-for.patch queue-6.1/virt-sev-guest-return-eio-if-certificate-buffer-is-not-large-enough.patch queue-6.1/kvm-svm-fix-potential-overflow-in-sev-s-send-receive_update_data.patch queue-6.1/crypto-ccp-flush-the-sev-es-tmr-memory-before-giving.patch