| Message ID | ZRvzdlvlbX4+eIln@work (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v2,next] cxgb4/ch_ktls: Fix undefined behavior bug in struct chcr_ktls_ofld_ctx_tx | expand |
2023-10-03, 12:56:54 +0200, Gustavo A. R. Silva wrote: > `struct tls_offload_context_tx` is a flexible structure, which means > that it contains a flexible-array member at the bottom. This could > potentially lead to an overwrite of the objects following `base` in > `struct chcr_ktls_ofld_ctx_tx` at run-time. > > Notice that flexible-array member `driver_state` in `struct > tls_offload_context_tx` can grow up to 16 bytes: > > | include/net/tls.h-170: > | #define TLS_DRIVER_STATE_SIZE_TX 16 > > | include/net/tls.h-173: > | #define TLS_OFFLOAD_CONTEXT_SIZE_TX \ > | (sizeof(struct tls_offload_context_tx) + TLS_DRIVER_STATE_SIZE_TX) > > | net/tls/tls_device.c-1119: > | offload_ctx = kzalloc(TLS_OFFLOAD_CONTEXT_SIZE_TX, GFP_KERNEL); > > Fix this by placing the declaration of object `base` at the end of > `struct chcr_ktls_ofld_ctx_tx`. AFAIU, chcr_ktls_ofld_ctx_tx just misuses the extra space allocated by tls_set_device_offload. There's no bug, but the code is a bit confusing. I don't think this patch works, since chcr_ktls doesn't allocate its own memory for chcr_ktls_ofld_ctx_tx. As part of a series of cleanups that I'll submit soon (hopefully this week), I updated chcr_ktls to use the driver_state part of tls_offload_context_tx (instead of the cast in chcr_get_ktls_tx_context), and then removed the flexarrays from tls_offload_context_tx and tls_offload_context_rx (since they're actually a fixed size).
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.h b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.h index 10572dc55365..35e34e3db663 100644 --- a/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.h +++ b/drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.h @@ -68,8 +68,8 @@ struct chcr_ktls_info { }; struct chcr_ktls_ofld_ctx_tx { - struct tls_offload_context_tx base; struct chcr_ktls_info *chcr_info; + struct tls_offload_context_tx base; }; struct chcr_ktls_uld_ctx {
`struct tls_offload_context_tx` is a flexible structure, which means that it contains a flexible-array member at the bottom. This could potentially lead to an overwrite of the objects following `base` in `struct chcr_ktls_ofld_ctx_tx` at run-time. Notice that flexible-array member `driver_state` in `struct tls_offload_context_tx` can grow up to 16 bytes: | include/net/tls.h-170: | #define TLS_DRIVER_STATE_SIZE_TX 16 | include/net/tls.h-173: | #define TLS_OFFLOAD_CONTEXT_SIZE_TX \ | (sizeof(struct tls_offload_context_tx) + TLS_DRIVER_STATE_SIZE_TX) | net/tls/tls_device.c-1119: | offload_ctx = kzalloc(TLS_OFFLOAD_CONTEXT_SIZE_TX, GFP_KERNEL); Fix this by placing the declaration of object `base` at the end of `struct chcr_ktls_ofld_ctx_tx`. -Wflex-array-member-not-at-end is coming in GCC-14, and we are getting ready to enable it globally. Fixes: 34aba2c45024 ("cxgb4/chcr : Register to tls add and del callback") Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- Changes in v2: - Update changelog text: mention -Wflex-array-member-not-at-end. v1: - Link: https://lore.kernel.org/linux-hardening/ZRvyysCUTqA7aXN4@work/ drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)