CVE-2023-54155

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net: core: remove unnecessary frame_sz check in bpf_xdp_adjust_tail()<br /> <br /> Syzkaller reported the following issue:<br /> =======================================<br /> Too BIG xdp-&gt;frame_sz = 131072<br /> WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121<br /> ____bpf_xdp_adjust_tail net/core/filter.c:4121 [inline]<br /> WARNING: CPU: 0 PID: 5020 at net/core/filter.c:4121<br /> bpf_xdp_adjust_tail+0x466/0xa10 net/core/filter.c:4103<br /> ...<br /> Call Trace:<br /> <br /> bpf_prog_4add87e5301a4105+0x1a/0x1c<br /> __bpf_prog_run include/linux/filter.h:600 [inline]<br /> bpf_prog_run_xdp include/linux/filter.h:775 [inline]<br /> bpf_prog_run_generic_xdp+0x57e/0x11e0 net/core/dev.c:4721<br /> netif_receive_generic_xdp net/core/dev.c:4807 [inline]<br /> do_xdp_generic+0x35c/0x770 net/core/dev.c:4866<br /> tun_get_user+0x2340/0x3ca0 drivers/net/tun.c:1919<br /> tun_chr_write_iter+0xe8/0x210 drivers/net/tun.c:2043<br /> call_write_iter include/linux/fs.h:1871 [inline]<br /> new_sync_write fs/read_write.c:491 [inline]<br /> vfs_write+0x650/0xe40 fs/read_write.c:584<br /> ksys_write+0x12f/0x250 fs/read_write.c:637<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80<br /> entry_SYSCALL_64_after_hwframe+0x63/0xcd<br /> <br /> xdp-&gt;frame_sz &gt; PAGE_SIZE check was introduced in commit c8741e2bfe87<br /> ("xdp: Allow bpf_xdp_adjust_tail() to grow packet size"). But Jesper<br /> Dangaard Brouer noted that after introducing the<br /> xdp_init_buff() which all XDP driver use - it&amp;#39;s safe to remove this<br /> check. The original intend was to catch cases where XDP drivers have<br /> not been updated to use xdp.frame_sz, but that is not longer a concern<br /> (since xdp_init_buff).<br /> <br /> Running the initial syzkaller repro it was discovered that the<br /> contiguous physical memory allocation is used for both xdp paths in<br /> tun_get_user(), e.g. tun_build_skb() and tun_alloc_skb(). It was also<br /> stated by Jesper Dangaard Brouer that XDP can<br /> work on higher order pages, as long as this is contiguous physical<br /> memory (e.g. a page).