Commit 3482062c786c for kernel

commit 3482062c786ce4233f8ed3224d824184f53ec154
Author: Richard Fitzgerald <rf@opensource.cirrus.com>
Date:   Mon Sep 14 13:26:11 2026 +0100

    ASoC: cs-amp-lib: Prevent NULL pointer if efi variable is zero length

    In cs_amp_alloc_get_efi_variable() the first call to
    cs_amp_get_efi_variable() might return EFI_SUCCESS if the variable
    exists with zero length. Trap this and return -ENOENT to prevent
    returning an unexpected NULL pointer.

    The first cs_amp_get_efi_variable() call was assumed to return
    EFI_BUFFER_TOO_SMALL if the variable existed, but if instead it
    returned EFI_SUCCESS this would be converted to 0 by
    cs_amp_convert_efi_status() and then be returned as a NULL pointer.

    Fixes: 00fd40bc7acec ("ASoC: cs-amp-lib: Support Dell SSIDExV2 UEFI variable")
    Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
    Link: https://patch.msgid.link/20260914122611.2783563-1-rf@opensource.cirrus.com
    Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/codecs/cs-amp-lib.c b/sound/soc/codecs/cs-amp-lib.c
index 41a9a5b005c6..9bc19d2e1639 100644
--- a/sound/soc/codecs/cs-amp-lib.c
+++ b/sound/soc/codecs/cs-amp-lib.c
@@ -317,6 +317,8 @@ static void *cs_amp_alloc_get_efi_variable(efi_char16_t *name,
 	unsigned long size = 0;

 	status = cs_amp_get_efi_variable(name, guid, NULL, &size, NULL);
+	if (status == EFI_SUCCESS)
+		return ERR_PTR(-ENOENT);
 	if (status != EFI_BUFFER_TOO_SMALL)
 		return ERR_PTR(cs_amp_convert_efi_status(status));