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CVE-2026-72135

tpm: Make the TPM character devices non-seekable

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.97, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

In the Linux kernel, the following vulnerability has been resolved: tpm: Make the TPM character devices non-seekable The TPM character devices expose a sequential command/response interface, but their open handlers leave FMODE_PREAD and FMODE_PWRITE enabled. After a command leaves a response pending, pread(fd, buf, 16, 0x1400) passes 0x1400 as *off to tpm_common_read(). The transfer length is bounded by response_length, but the offset is used unchecked when forming data_buffer + *off. A sufficiently large offset therefore causes an out-of-bounds heap read through copy_to_user() and, if the copy succeeds, an out-of-bounds zero-write through the following memset(). Positional I/O does not provide coherent semantics for this interface. An arbitrary pread offset cannot represent how much of a response has been consumed sequentially. The write callback always stores a command at the start of data_buffer, while pwrite() does not update file->f_pos and can leave the sequential read cursor stale. Call nonseekable_open() from both open handlers. This removes FMODE_PREAD and FMODE_PWRITE, causing positional reads and writes to fail with -ESPIPE before reaching the TPM callbacks, and explicitly marks the files non-seekable. Normal read() and write() continue to use the existing sequential f_pos cursor, leaving the response state machine unchanged. Tested on Linux 6.12 with KASAN and a swtpm TPM2 device: • sequential partial reads returned the complete response • pread() and preadv() with offset 0x1400 returned -ESPIPE • pwrite() and pwritev() with offset zero returned -ESPIPE • the pending response remained intact after the rejected operations • a subsequent normal command/response cycle completed normally • no KASAN report was produced.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in ed0ffc2c016629e40ba041ed0424a772d8b02e2c; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in 232dcf908eb7eb9d8046a9597975caf44270966e; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in dda695fab5e21f923d29e8cb01df256468ddfbd1; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in 9c513dabd4540f811585a2087f23069767a284da; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in 21a13f932972bc9836f58c44fcd47c62abdecd95; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in ada4b9a5087ea7f30dd8e4c6411a4fb6547eb1ed; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in 947b773caaa548672184df025271b29bdc80b0f1; From 9488585b21bef0df1217e510c7134905d1d376a7 · fixed in f20d61c22bcaf172d6790b6500e3838e532e71c8

  • Linux Linux

    5.0

  • KernelLinux

    From 5.0.0 · fixed in 5.10.261; From 5.11.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5

References 8

git.kernel.org