When I implemented virtio's hash-related features to tun/tap [1], I found tun/tap does not fill the entire region reserved for the virtio header, leaving some uninitialized hole in the middle of the buffer after read()/recvmesg().
This series fills the uninitialized hole. More concretely, the num_buffers field will be initialized with 1, and the other fields will be inialized with 0. Setting the num_buffers field to 1 is mandated by virtio 1.0 [2].
The change to virtio header is preceded by another change that refactors tun and tap to unify their virtio-related code.
[1]: https://lore.kernel.org/r/20241008-rss-v5-0-f3cf68df005d@daynix.com [2]: https://lore.kernel.org/r/20241227084256-mutt-send-email-mst@kernel.org/
Signed-off-by: Akihiko Odaki akihiko.odaki@daynix.com --- Changes in v4: - s/sz/vnet_hdr_len_sz/ for patch "tun: Decouple vnet handling" (Willem de Bruijn) - Reverted to add CONFIG_TUN_VNET. - Link to v3: https://lore.kernel.org/r/20250116-tun-v3-0-c6b2871e97f7@daynix.com
Changes in v3: - Dropped changes to fill the vnet header. - Splitted patch "tun: Unify vnet implementation". - Reverted spurious changes in patch "tun: Unify vnet implementation". - Merged tun_vnet.c into TAP. - Link to v2: https://lore.kernel.org/r/20250109-tun-v2-0-388d7d5a287a@daynix.com
Changes in v2: - Fixed num_buffers endian. - Link to v1: https://lore.kernel.org/r/20250108-tun-v1-0-67d784b34374@daynix.com
--- Akihiko Odaki (9): tun: Refactor CONFIG_TUN_VNET_CROSS_LE tun: Avoid double-tracking iov_iter length changes tun: Keep hdr_len in tun_get_user() tun: Decouple vnet from tun_struct tun: Decouple vnet handling tun: Extract the vnet handling code tap: Avoid double-tracking iov_iter length changes tap: Keep hdr_len in tap_get_user() tap: Use tun's vnet-related code
MAINTAINERS | 2 +- drivers/net/Kconfig | 5 ++ drivers/net/Makefile | 1 + drivers/net/tap.c | 172 ++++++------------------------------------ drivers/net/tun.c | 200 +++++++------------------------------------------ drivers/net/tun_vnet.c | 184 +++++++++++++++++++++++++++++++++++++++++++++ drivers/net/tun_vnet.h | 25 +++++++ 7 files changed, 267 insertions(+), 322 deletions(-) --- base-commit: a32e14f8aef69b42826cf0998b068a43d486a9e9 change-id: 20241230-tun-66e10a49b0c7
Best regards,