75 lines
2.6 KiB
Diff
75 lines
2.6 KiB
Diff
From 4e242d6e08ad1d85b832e158cd0eafcb8f3f76a1 Mon Sep 17 00:00:00 2001
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From: Linus Walleij <linus.walleij@linaro.org>
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Date: Tue, 30 May 2023 22:40:31 +0200
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Subject: [PATCH v3] mtd: cfi_cmdset_0001: Byte swap OTP info
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Currently the offset into the device when looking for OTP
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bits can go outside of the address of the MTD NOR devices,
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and if that memory isn't readable, bad things happen
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on the IXP4xx (added prints that illustrate the problem before
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the crash):
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cfi_intelext_otp_walk walk OTP on chip 0 start at reg_prot_offset 0x00000100
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ixp4xx_copy_from copy from 0x00000100 to 0xc880dd78
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cfi_intelext_otp_walk walk OTP on chip 0 start at reg_prot_offset 0x12000000
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ixp4xx_copy_from copy from 0x12000000 to 0xc880dd78
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8<--- cut here ---
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Unable to handle kernel paging request at virtual address db000000
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[db000000] *pgd=00000000
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(...)
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This happens in this case because the IXP4xx is big endian and
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the 32- and 16-bit fields in the struct cfi_intelext_otpinfo are not
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properly byteswapped. Compare to how the code in read_pri_intelext()
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byteswaps the fields in struct cfi_pri_intelext.
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Adding a small byte swapping loop for the OTP in read_pri_intelext()
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and the crash goes away.
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The problem went unnoticed for many years until I enabled
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CONFIG_MTD_OTP on the IXP4xx as well, triggering the bug.
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Cc: Nicolas Pitre <npitre@baylibre.com>
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Cc: stable@vger.kernel.org
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Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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---
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ChangeLog v2->v3:
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- Move the byte swapping to a small loop in read_pri_intelext()
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so all bytes are swapped as we reach cfi_intelext_otp_walk().
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ChangeLog v1->v2:
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- Drill deeper and discover a big endian compatibility issue.
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---
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drivers/mtd/chips/cfi_cmdset_0001.c | 20 ++++++++++++++++++--
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1 file changed, 18 insertions(+), 2 deletions(-)
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--- a/drivers/mtd/chips/cfi_cmdset_0001.c
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+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
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@@ -421,9 +421,25 @@ read_pri_intelext(struct map_info *map,
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extra_size = 0;
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/* Protection Register info */
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- if (extp->NumProtectionFields)
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+ if (extp->NumProtectionFields) {
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+ struct cfi_intelext_otpinfo *otp =
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+ (struct cfi_intelext_otpinfo *)&extp->extra[0];
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+
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extra_size += (extp->NumProtectionFields - 1) *
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- sizeof(struct cfi_intelext_otpinfo);
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+ sizeof(struct cfi_intelext_otpinfo);
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+
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+ if (extp_size >= sizeof(*extp) + extra_size) {
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+ int i;
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+
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+ /* Do some byteswapping if necessary */
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+ for (i = 0; i < extp->NumProtectionFields - 1; i++) {
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+ otp->ProtRegAddr = le32_to_cpu(otp->ProtRegAddr);
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+ otp->FactGroups = le16_to_cpu(otp->FactGroups);
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+ otp->UserGroups = le16_to_cpu(otp->UserGroups);
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+ otp++;
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+ }
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+ }
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+ }
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}
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if (extp->MinorVersion >= '1') {
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