Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: usb: storage: Fix memory leak in USB bulk transport A kernel memory leak was identified by the 'ioctl_sg01' test from Linux Test Project (LTP). The following bytes were mainly observed: 0x53425355. When USB storage devices incorrectly skip the data phase with status data, the code extracts/validates the CSW from the sg buffer, but fails to clear it afterwards. This leaves status protocol data in srb's transfer buffer, such as the US_BULK_CS_SIGN 'USBS' signature observed here. Thus, this can lead to USB protocols leaks to user space through SCSI generic (/dev/sg*) interfaces, such as the one seen here when the LTP test requested 512 KiB. Fix the leak by zeroing the CSW data in srb's transfer buffer immediately after the validation of devices that skip data phase. Note: Differently from CVE-2018-1000204, which fixed a big leak by zero- ing pages at allocation time, this leak occurs after allocation, when USB protocol data is written to already-allocated sg pages.

Affected versions

Linux: a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before 83f0241959831586d9b6d47f6bd5d3dec8f43bf0 (git); a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before 4ba515dfff7eeca369ab85cdbb3f3b231c71720c (git); a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before 467fec3cefbeb9e3ea80f457da9a5666a71ca0d0 (git); a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before cb1401b5bcc2feb5b038fc4b512e5968b016e05e (git); a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before 0f18eac44c5668204bf6eebb01ddb369ac56932b (git); a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before 5b815ddb3f5560fac35b16de3a2a22d5f81c5993 (git); a45b599ad808c3c982fdcdc12b0b8611c2f92824 through before 41e99fe2005182139b1058db71f0d241f8f0078c (git); 582802e7c617cfb07cc15f280c128e6decbc57b8 (git); 58b7ce6f9ef2367f86384b20458642945993b816 (git); 93314640426ddb6af618d0802e622f6fa771792c (git); ad2518320bc440ed3db072e2444a1bb226a9cf7a (git); d827bea2d18c07ba514f7d48cde49f90da9a1384 (git); 39169410574503c6e901de1aa6eac5108475e017 (git); 3.16.58 through before 3.17 (semver); 3.18.110 through before 3.19 (semver); 4.4.133 through before 4.5 (semver); 4.9.103 through before 4.10 (semver); 4.14.44 through before 4.15 (semver); 4.16.12 through before 4.17 (semver); 4.17 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.