5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Babanpreet Singh [ Upstream commit 4d3721b204f961e905714954ff95633337b768e3 ] ds2482_wait_1wire_idle() returns the status register value (0..255) on success, or a negative value on I2C failure: -1 when selecting the status register fails, or a negative errno from i2c_smbus_read_byte(). ds2482_w1_triplet() feeds that result into "return (status >> 5);" without checking for errors, and the function returns u8. For a negative status the arithmetic shift keeps the sign and the u8 truncation fabricates a triplet result whose meaning depends on the errno value: -1 and -EIO happen to become 0xff, whose set low bits make w1_search() abort, but -ETIMEDOUT (-110 >> 5 = -4) becomes 0xfc - "devices responded on both branches, wrote 1" - and -EOPNOTSUPP (-95 >> 5 = -3) becomes 0xfd - "only the zero branch responded". w1_search() then continues the ROM search with a fabricated direction bit instead of aborting, and the corrupted id is either rejected by the ROM CRC (existing device missed) or registers a phantom slave. The function already defines an in-band error value: status is initialized to (3 << 5), which decodes to 3 (both branch bits set, "no device responded") and makes w1_search() terminate the search when sending the triplet command fails. Decode a negative status to the same value. Found by smatch: drivers/w1/masters/ds2482.c:314 ds2482_w1_triplet() warn: signedness bug returning '(-67108864)' Fixes: baf12ae29ab4 ("[PATCH] W1: Add the DS2482 I2C-to-w1 bridge driver.") Assisted-by: Claude:claude-sonnet-5 Signed-off-by: Babanpreet Singh Link: https://patch.msgid.link/20260714041011.7-1-bbnpreetsingh@gmail.com Signed-off-by: Krzysztof Kozlowski Signed-off-by: Sasha Levin --- drivers/w1/masters/ds2482.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/w1/masters/ds2482.c b/drivers/w1/masters/ds2482.c index b471779c3e2c0..c7ba3e98ec0c3 100644 --- a/drivers/w1/masters/ds2482.c +++ b/drivers/w1/masters/ds2482.c @@ -312,6 +312,10 @@ static u8 ds2482_w1_triplet(void *data, u8 dbit) mutex_unlock(&pdev->access_lock); + /* On bus error, decode to 3 (no device responded) to abort the search */ + if (status < 0) + status = 3 << 5; + /* Decode the status */ return (status >> 5); } -- 2.53.0