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f20d61c22b
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:
|
||
|---|---|---|
| .. | ||
| agp | ||
| hw_random | ||
| ipmi | ||
| tpm | ||
| xilinx_hwicap | ||
| xillybus | ||
| adi.c | ||
| apm-emulation.c | ||
| bsr.c | ||
| ds1620.c | ||
| dsp56k.c | ||
| hangcheck-timer.c | ||
| hpet.c | ||
| Kconfig | ||
| lp.c | ||
| Makefile | ||
| mem.c | ||
| misc_minor_kunit.c | ||
| misc.c | ||
| nsc_gpio.c | ||
| nvram.c | ||
| nwbutton.c | ||
| nwbutton.h | ||
| nwflash.c | ||
| pc8736x_gpio.c | ||
| powernv-op-panel.c | ||
| ppdev.c | ||
| ps3flash.c | ||
| random.c | ||
| scx200_gpio.c | ||
| sonypi.c | ||
| tlclk.c | ||
| toshiba.c | ||
| ttyprintk.c | ||
| uv_mmtimer.c | ||
| virtio_console.c | ||