linux-kernel - [PATCH] soc: qcom: mdt_loader: Deal with zero e

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Message-Id: <20250730-mdt-loader-shentsize-zero-v1-1-04f43186229c@oss.qualcomm.com>
Date: Wed, 30 Jul 2025 15:51:51 -0500
From: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Val Packett <val@...kett.cool>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Bjorn Andersson <bjorn.andersson@....qualcomm.com>
Subject: [PATCH] soc: qcom: mdt_loader: Deal with zero e_shentsize

Firmware that doesn't provide section headers leave both e_shentsize and
e_shnum 0, which obvious isn't compatible with the newly introduced
stricter checks.

Make the section-related checks conditional on either of these values
being non-zero.

Fixes: 9f9967fed9d0 ("soc: qcom: mdt_loader: Ensure we don't read past the ELF header")
Reported-by: Val Packett <val@...kett.cool>
Closes: https://lore.kernel.org/all/ece307c3-7d65-440f-babd-88cf9705b908@packett.cool/
Reported-by: Neil Armstrong <neil.armstrong@...aro.org>
Closes: https://lore.kernel.org/all/aec9cd03-6fc2-4dc8-b937-8b7cf7bf4128@linaro.org/
Signed-off-by: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
---
 drivers/soc/qcom/mdt_loader.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
index 0ca268bdf1f8c579b36a04fd94417be172fc1099..5710ac0c07a8c8a56110e3fc5e30b8610e106449 100644
--- a/drivers/soc/qcom/mdt_loader.c
+++ b/drivers/soc/qcom/mdt_loader.c
@@ -39,12 +39,14 @@ static bool mdt_header_valid(const struct firmware *fw)
 	if (phend > fw->size)
 		return false;
 
-	if (ehdr->e_shentsize != sizeof(struct elf32_shdr))
-		return false;
+	if (ehdr->e_shentsize || ehdr->e_shnum) {
+		if (ehdr->e_shentsize != sizeof(struct elf32_shdr))
+			return false;
 
-	shend = size_add(size_mul(sizeof(struct elf32_shdr), ehdr->e_shnum), ehdr->e_shoff);
-	if (shend > fw->size)
-		return false;
+		shend = size_add(size_mul(sizeof(struct elf32_shdr), ehdr->e_shnum), ehdr->e_shoff);
+		if (shend > fw->size)
+			return false;
+	}
 
 	return true;
 }

---
base-commit: 79fb37f39b77bbf9a56304e9af843cd93a7a1916
change-id: 20250730-mdt-loader-shentsize-zero-8c99653b6343

Best regards,
-- 
Bjorn Andersson <bjorn.andersson@....qualcomm.com>