spi: fsl-cpm: Check length parity before switching to 16 bit mode

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commit 1417927df8 upstream.

Commit fc96ec826b ("spi: fsl-cpm: Use 16 bit mode for large transfers
with even size") failed to make sure that the size is really even
before switching to 16 bit mode. Until recently the problem went
unnoticed because kernfs uses a pre-allocated bounce buffer of size
PAGE_SIZE for reading EEPROM.

But commit 8ad6249c51 ("eeprom: at25: convert to spi-mem API")
introduced an additional dynamically allocated bounce buffer whose size
is exactly the size of the transfer, leading to a buffer overrun in
the fsl-cpm driver when that size is odd.

Add the missing length parity verification and remain in 8 bit mode
when the length is not even.

Fixes: fc96ec826b ("spi: fsl-cpm: Use 16 bit mode for large transfers with even size")
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/all/638496dd-ec60-4e53-bad7-eb657f67d580@csgroup.eu/
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Sverdlin Alexander <alexander.sverdlin@siemens.com>
Link: https://patch.msgid.link/3c4d81c3923c93f95ec56702a454744a4bad3cfc.1763627618.git.christophe.leroy@csgroup.eu
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Christophe Leroy 2025-11-20 09:34:49 +01:00 • committed by Greg Kroah-Hartman

parent 7e086c97dd

commit be0b613198

1 changed files with 1 additions and 1 deletions

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drivers/spi/spi-fsl-spi.c

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