6.7-stable review patch. If anyone has any objections, please let me know.
------------------
From: Maciej Fijalkowski maciej.fijalkowski@intel.com
[ Upstream commit c5114710c8ce86b8317e9b448f4fd15c711c2a82 ]
Currently when packet is shrunk via bpf_xdp_adjust_tail() and memory type is set to MEM_TYPE_XSK_BUFF_POOL, null ptr dereference happens:
[1136314.192256] BUG: kernel NULL pointer dereference, address: 0000000000000034 [1136314.203943] #PF: supervisor read access in kernel mode [1136314.213768] #PF: error_code(0x0000) - not-present page [1136314.223550] PGD 0 P4D 0 [1136314.230684] Oops: 0000 [#1] PREEMPT SMP NOPTI [1136314.239621] CPU: 8 PID: 54203 Comm: xdpsock Not tainted 6.6.0+ #257 [1136314.250469] Hardware name: Intel Corporation S2600WFT/S2600WFT, BIOS SE5C620.86B.02.01.0008.031920191559 03/19/2019 [1136314.265615] RIP: 0010:__xdp_return+0x6c/0x210 [1136314.274653] Code: ad 00 48 8b 47 08 49 89 f8 a8 01 0f 85 9b 01 00 00 0f 1f 44 00 00 f0 41 ff 48 34 75 32 4c 89 c7 e9 79 cd 80 ff 83 fe 03 75 17 <f6> 41 34 01 0f 85 02 01 00 00 48 89 cf e9 22 cc 1e 00 e9 3d d2 86 [1136314.302907] RSP: 0018:ffffc900089f8db0 EFLAGS: 00010246 [1136314.312967] RAX: ffffc9003168aed0 RBX: ffff8881c3300000 RCX: 0000000000000000 [1136314.324953] RDX: 0000000000000000 RSI: 0000000000000003 RDI: ffffc9003168c000 [1136314.336929] RBP: 0000000000000ae0 R08: 0000000000000002 R09: 0000000000010000 [1136314.348844] R10: ffffc9000e495000 R11: 0000000000000040 R12: 0000000000000001 [1136314.360706] R13: 0000000000000524 R14: ffffc9003168aec0 R15: 0000000000000001 [1136314.373298] FS: 00007f8df8bbcb80(0000) GS:ffff8897e0e00000(0000) knlGS:0000000000000000 [1136314.386105] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1136314.396532] CR2: 0000000000000034 CR3: 00000001aa912002 CR4: 00000000007706f0 [1136314.408377] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [1136314.420173] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [1136314.431890] PKRU: 55555554 [1136314.439143] Call Trace: [1136314.446058] <IRQ> [1136314.452465] ? __die+0x20/0x70 [1136314.459881] ? page_fault_oops+0x15b/0x440 [1136314.468305] ? exc_page_fault+0x6a/0x150 [1136314.476491] ? asm_exc_page_fault+0x22/0x30 [1136314.484927] ? __xdp_return+0x6c/0x210 [1136314.492863] bpf_xdp_adjust_tail+0x155/0x1d0 [1136314.501269] bpf_prog_ccc47ae29d3b6570_xdp_sock_prog+0x15/0x60 [1136314.511263] ice_clean_rx_irq_zc+0x206/0xc60 [ice] [1136314.520222] ? ice_xmit_zc+0x6e/0x150 [ice] [1136314.528506] ice_napi_poll+0x467/0x670 [ice] [1136314.536858] ? ttwu_do_activate.constprop.0+0x8f/0x1a0 [1136314.546010] __napi_poll+0x29/0x1b0 [1136314.553462] net_rx_action+0x133/0x270 [1136314.561619] __do_softirq+0xbe/0x28e [1136314.569303] do_softirq+0x3f/0x60
This comes from __xdp_return() call with xdp_buff argument passed as NULL which is supposed to be consumed by xsk_buff_free() call.
To address this properly, in ZC case, a node that represents the frag being removed has to be pulled out of xskb_list. Introduce appropriate xsk helpers to do such node operation and use them accordingly within bpf_xdp_adjust_tail().
Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Acked-by: Magnus Karlsson magnus.karlsson@intel.com # For the xsk header part Signed-off-by: Maciej Fijalkowski maciej.fijalkowski@intel.com Link: https://lore.kernel.org/r/20240124191602.566724-4-maciej.fijalkowski@intel.c... Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/xdp_sock_drv.h | 26 +++++++++++++++++++++++ net/core/filter.c | 42 ++++++++++++++++++++++++++++++++------ 2 files changed, 62 insertions(+), 6 deletions(-)
diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h index 7290eb721c07..5425f7ad5ebd 100644 --- a/include/net/xdp_sock_drv.h +++ b/include/net/xdp_sock_drv.h @@ -147,6 +147,23 @@ static inline struct xdp_buff *xsk_buff_get_frag(struct xdp_buff *first) return ret; }
+static inline void xsk_buff_del_tail(struct xdp_buff *tail) +{ + struct xdp_buff_xsk *xskb = container_of(tail, struct xdp_buff_xsk, xdp); + + list_del(&xskb->xskb_list_node); +} + +static inline struct xdp_buff *xsk_buff_get_tail(struct xdp_buff *first) +{ + struct xdp_buff_xsk *xskb = container_of(first, struct xdp_buff_xsk, xdp); + struct xdp_buff_xsk *frag; + + frag = list_last_entry(&xskb->pool->xskb_list, struct xdp_buff_xsk, + xskb_list_node); + return &frag->xdp; +} + static inline void xsk_buff_set_size(struct xdp_buff *xdp, u32 size) { xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM; @@ -310,6 +327,15 @@ static inline struct xdp_buff *xsk_buff_get_frag(struct xdp_buff *first) return NULL; }
+static inline void xsk_buff_del_tail(struct xdp_buff *tail) +{ +} + +static inline struct xdp_buff *xsk_buff_get_tail(struct xdp_buff *first) +{ + return NULL; +} + static inline void xsk_buff_set_size(struct xdp_buff *xdp, u32 size) { } diff --git a/net/core/filter.c b/net/core/filter.c index 1737884be52f..6575288b8580 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -83,6 +83,7 @@ #include <net/netfilter/nf_conntrack_bpf.h> #include <net/netkit.h> #include <linux/un.h> +#include <net/xdp_sock_drv.h>
#include "dev.h"
@@ -4094,6 +4095,40 @@ static int bpf_xdp_frags_increase_tail(struct xdp_buff *xdp, int offset) return 0; }
+static void bpf_xdp_shrink_data_zc(struct xdp_buff *xdp, int shrink, + struct xdp_mem_info *mem_info, bool release) +{ + struct xdp_buff *zc_frag = xsk_buff_get_tail(xdp); + + if (release) { + xsk_buff_del_tail(zc_frag); + __xdp_return(NULL, mem_info, false, zc_frag); + } else { + zc_frag->data_end -= shrink; + } +} + +static bool bpf_xdp_shrink_data(struct xdp_buff *xdp, skb_frag_t *frag, + int shrink) +{ + struct xdp_mem_info *mem_info = &xdp->rxq->mem; + bool release = skb_frag_size(frag) == shrink; + + if (mem_info->type == MEM_TYPE_XSK_BUFF_POOL) { + bpf_xdp_shrink_data_zc(xdp, shrink, mem_info, release); + goto out; + } + + if (release) { + struct page *page = skb_frag_page(frag); + + __xdp_return(page_address(page), mem_info, false, NULL); + } + +out: + return release; +} + static int bpf_xdp_frags_shrink_tail(struct xdp_buff *xdp, int offset) { struct skb_shared_info *sinfo = xdp_get_shared_info_from_buff(xdp); @@ -4108,12 +4143,7 @@ static int bpf_xdp_frags_shrink_tail(struct xdp_buff *xdp, int offset)
len_free += shrink; offset -= shrink; - - if (skb_frag_size(frag) == shrink) { - struct page *page = skb_frag_page(frag); - - __xdp_return(page_address(page), &xdp->rxq->mem, - false, NULL); + if (bpf_xdp_shrink_data(xdp, frag, shrink)) { n_frags_free++; } else { skb_frag_size_sub(frag, shrink);