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w1: ds28e17: reject an oversize length on an I2C block read

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w1_f19_i2c_master_transfer() is the master_xfer for the DS28E17 1-Wire
to I2C bridge. On an I2C_M_RECV_LEN read, it takes the length from the
device. The downstream slave puts a length byte in buf[0]. The driver
then reads that many bytes into buf[1] with w1_f19_i2c_read().

buf[0] is controlled by the device and can be 0 to 255.
w1_f19_i2c_read() only rejects a zero count. The caller buffer is
I2C_SMBUS_BLOCK_MAX + 2, so 34 bytes. A length above 32 makes the read
run past it, up to about 222 bytes out of bounds.

The SMBus core does check buf[0] against I2C_SMBUS_BLOCK_MAX. That
check runs after master_xfer returns. By then the write is already
done. i2c-algo-bit rejects an oversize length before it copies, and
returns -EPROTO.

Reject a length above I2C_SMBUS_BLOCK_MAX at both RECV_LEN sites, the
same way i2c-algo-bit does.

Fixes: ebc4768ac4 ("add w1_ds28e17 driver for the DS28E17 Onewire to I2C master bridge")
Cc: stable@vger.kernel.org
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://patch.msgid.link/20260629121043.199487-1-maoyixie.tju@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
This commit is contained in:
Maoyi Xie
2026-07-04 10:21:38 +02:00
committed by Krzysztof Kozlowski
parent faa63a51be
commit 169ae5e65e
1 changed files with 8 additions and 0 deletions
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drivers/w1/slaves/w1_ds28e17.c
+8
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@@ -389,6 +389,10 @@ static int w1_f19_i2c_master_transfer(struct i2c_adapter *adapter,
* another simple read in that case.
*/
if (msgs[i+1].flags & I2C_M_RECV_LEN) {
if (msgs[i+1].buf[0] > I2C_SMBUS_BLOCK_MAX) {
i = -EPROTO;
goto error;
}
result = w1_f19_i2c_read(sl, msgs[i+1].addr,
&(msgs[i+1].buf[1]), msgs[i+1].buf[0]);
if (result < 0) {
@@ -415,6 +419,10 @@ static int w1_f19_i2c_master_transfer(struct i2c_adapter *adapter,
* another simple read in that case.
*/
if (msgs[i].flags & I2C_M_RECV_LEN) {
if (msgs[i].buf[0] > I2C_SMBUS_BLOCK_MAX) {
i = -EPROTO;
goto error;
}
result = w1_f19_i2c_read(sl,
msgs[i].addr,
&(msgs[i].buf[1]),