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Jaewon Yang
9c513dabd4
commitf20d61c22bupstream. 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. Fixes:9488585b21("tpm: add support for partial reads") Link: https://lore.kernel.org/all/20260710090217.191289-1-yong010301@gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Jaewon Yang <yong010301@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.