[PATCH net-next v5 0/2] vsock/test: check for null-ptr-deref when transport changes

[Luigi Leonardi <leonardi@redhat.com>]

This series introduces a new test that checks for a null pointer 
dereference that may happen when there is a transport change[1]. This 
bug was fixed in [2].

Note that this test *cannot* fail, it hangs if it triggers a kernel
oops. The intended use-case is to run it and then check if there is any 
oops in the dmesg.

This test is based on Hyunwoo Kim's[3] and Michal's python 
reproducers[4].

[1]https://lore.kernel.org/netdev/Z2LvdTTQR7dBmPb5@v4bel-B760M-AORUS-ELITE-AX/
[2]https://lore.kernel.org/netdev/20250110083511.30419-1-sgarzare@redhat.com/
[3]https://lore.kernel.org/netdev/Z2LvdTTQR7dBmPb5@v4bel-B760M-AORUS-ELITE-AX/#t
[4]https://lore.kernel.org/netdev/2b3062e3-bdaa-4c94-a3c0-2930595b9670@rbox.co/

Signed-off-by: Luigi Leonardi <leonardi@redhat.com>
---
Changes in v5:
- Addressed Stefano's comments:
    - Use a macro for G2H transport detection
    - Improved commits and comments text
    - Rebased on latest net-next
- Link to v4: 
https://lore.kernel.org/r/20250624-test_vsock-v4-1-087c9c8e25a2@redhat.com

Changes in v4:
- Addressed Stefano's comments:
    - Minor style changes
    - Use `get_transports()` to print a warning when a G2H transport is 
    loaded
    - Removed check on second connect: Because the first connect is 
    interrupted, the socket is in an unspecified state (see man connect) 
    . This can cause strange and unexpected behaviors (connect returning 
    success on a non-existing CID).

- Link to v3: 
https://lore.kernel.org/r/20250611-test_vsock-v3-1-8414a2d4df62@redhat.com

Sorry, this took waaay longer than expected.

Changes in v3:
Addressed Stefano's and Michal's comments:
    - Added the splat text to the commit commessage.
    - Introduced commit hash that fixes the bug.
    - Not using perror anymore on pthread_* functions.
    - Listener is just created once.

- Link to v2:
https://lore.kernel.org/r/20250314-test_vsock-v2-1-3c0a1d878a6d@redhat.com

Changes in v2:
- Addressed Stefano's comments:
    - Timeout is now using current_nsec()
    - Check for return values
    - Style issues
- Added Hyunwoo Kim to Suggested-by
- Link to v1: 
https://lore.kernel.org/r/20250306-test_vsock-v1-0-0320b5accf92@redhat.com

---
Luigi Leonardi (2):
      vsock/test: Add macros to identify transports
      vsock/test: Add test for null ptr deref when transport changes

 tools/testing/vsock/Makefile     |   1 +
 tools/testing/vsock/util.h       |   4 +
 tools/testing/vsock/vsock_test.c | 170 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 175 insertions(+)
---
base-commit: 647496422ba9d2784fb8e15b3fda7fe801b1f2ff
change-id: 20250306-test_vsock-3e77a9c7a245

Best regards,
-- 
Luigi Leonardi <leonardi@redhat.com>