[PATCH v3 0/3] lib: sbi: fix shared memory double-fetch in DBTR and SSE

[liutong]

M-mode validates a request held in S-mode shared memory and then reads
that same memory again in order to act on it. S-mode may rewrite the
memory in between, so the values programmed into M-mode state are not
necessarily the values that were validated.

  - sbi_dbtr_install_trig() re-reads each entry in three passes
  - sbi_dbtr_update_trig() re-reads each entry four times
  - sse_write_attrs() re-reads the attributes in a check pass and again
    in an apply pass

Each is fixed by copying the request once and making every later
decision against that copy.

Himanshu pointed out on v2 that the install_trig patch was written
against a shape of the function that no longer exists upstream: the
per-slot capability matching and the dry-run slot allocation added
since then re-read shared memory independently, so the race was still
open. That patch is reworked here against current master, with the
copy threaded through those paths.

The other half of the previous six patch series, three integer overflow
fixes and one unmap fix, is sent separately as "[PATCH v3 0/4] lib:
sbi: fix integer overflows in shared memory bounds checks". Both halves
apply to master in either order.

Changes in v3:
- Rebased onto current master
- Split out of the previous six patch series
- Subject prefixes changed to "lib: sbi: dbtr:" and "lib: sbi: sse:" to
  match the rest of those files' history
- 1/3: reworked, see the patch for details
- 2/3: new in v3
- 3/3: added a bound check inside sse_write_attrs()
- Dropped the DBTR shared memory range check that was v2 3/6. Pengpeng
  Hou sent the same fix in "lib: sbi: dbtr: validate complete shared
  memory range", which already carries a Reviewed-by. Note that
  Himanshu's remark on v2 3/6, that the "dom &&" guard skips the check
  entirely when dom is NULL, applies to that patch as well and is left
  to its thread.
- Link to v2: https://lore.kernel.org/opensbi/20260731103405.1535818-1-liutong@iscas.ac.cn/

liutong (3):
  lib: sbi: dbtr: fix shared memory double-fetch in install_trig
  lib: sbi: dbtr: fix shared memory double-fetch in update_trig
  lib: sbi: sse: fix shared memory double-fetch in sse_write_attrs

 lib/sbi/sbi_dbtr.c | 226 +++++++++++++++++++++++++++------------------
 lib/sbi/sbi_sse.c  |  26 ++++--
 2 files changed, 158 insertions(+), 94 deletions(-)


base-commit: 3593a5facc4c6938b90429a6973ba9ee21fc5899
-- 
2.34.1