Re: [PATCH net-next] Prevent overflow of sk_msg in sk_msg_clone()

[John Fastabend <john.fastabend@gmail.com>]

On 12/21/18 7:55 AM, Vakul Garg wrote:
> Fixed function sk_msg_clone() to prevent overflow of 'dst' while adding
> pages in scatterlist entries. The overflow of 'dst' causes crash in kernel
> tls module while doing record encryption.
> 
> Crash fixed by this patch.
> 
> [   78.796119] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
> [   78.804900] Mem abort info:
> [   78.807683]   ESR = 0x96000004
> [   78.810744]   Exception class = DABT (current EL), IL = 32 bits
> [   78.816677]   SET = 0, FnV = 0
> [   78.819727]   EA = 0, S1PTW = 0
> [   78.822873] Data abort info:
> [   78.825759]   ISV = 0, ISS = 0x00000004
> [   78.829600]   CM = 0, WnR = 0
> [   78.832576] user pgtable: 4k pages, 48-bit VAs, pgdp = 00000000bf8ee311
> [   78.839195] [0000000000000008] pgd=0000000000000000
> [   78.844081] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [   78.849642] Modules linked in: tls xt_conntrack ipt_REJECT nf_reject_ipv4 ip6table_filter ip6_tables xt_CHECKSUM cpve cpufreq_conservative lm90 ina2xx crct10dif_ce
> [   78.865377] CPU: 0 PID: 6007 Comm: openssl Not tainted 4.20.0-rc6-01647-g754d5da63145-dirty #107
> [   78.874149] Hardware name: LS1043A RDB Board (DT)
> [   78.878844] pstate: 60000005 (nZCv daif -PAN -UAO)
> [   78.883632] pc : scatterwalk_copychunks+0x164/0x1c8
> [   78.888500] lr : scatterwalk_copychunks+0x160/0x1c8
> [   78.893366] sp : ffff00001d04b600
> [   78.896668] x29: ffff00001d04b600 x28: ffff80006814c680
> [   78.901970] x27: 0000000000000000 x26: ffff80006c8de786
> [   78.907272] x25: ffff00001d04b760 x24: 000000000000001a
> [   78.912573] x23: 0000000000000006 x22: ffff80006814e440
> [   78.917874] x21: 0000000000000100 x20: 0000000000000000
> [   78.923175] x19: 000081ffffffffff x18: 0000000000000400
> [   78.928476] x17: 0000000000000008 x16: 0000000000000000
> [   78.933778] x15: 0000000000000100 x14: 0000000000000001
> [   78.939079] x13: 0000000000001080 x12: 0000000000000020
> [   78.944381] x11: 0000000000001080 x10: 00000000ffff0002
> [   78.949683] x9 : ffff80006814c248 x8 : 00000000ffff0000
> [   78.954985] x7 : ffff80006814c318 x6 : ffff80006c8de786
> [   78.960286] x5 : 0000000000000f80 x4 : ffff80006c8de000
> [   78.965588] x3 : 0000000000000000 x2 : 0000000000001086
> [   78.970889] x1 : ffff7e0001b74e02 x0 : 0000000000000000
> [   78.976192] Process openssl (pid: 6007, stack limit = 0x00000000291367f9)
> [   78.982968] Call trace:
> [   78.985406]  scatterwalk_copychunks+0x164/0x1c8
> [   78.989927]  skcipher_walk_next+0x28c/0x448
> [   78.994099]  skcipher_walk_done+0xfc/0x258
> [   78.998187]  gcm_encrypt+0x434/0x4c0
> [   79.001758]  tls_push_record+0x354/0xa58 [tls]
> [   79.006194]  bpf_exec_tx_verdict+0x1e4/0x3e8 [tls]
> [   79.010978]  tls_sw_sendmsg+0x650/0x780 [tls]
> [   79.015326]  inet_sendmsg+0x2c/0xf8
> [   79.018806]  sock_sendmsg+0x18/0x30
> [   79.022284]  __sys_sendto+0x104/0x138
> [   79.025935]  __arm64_sys_sendto+0x24/0x30
> [   79.029936]  el0_svc_common+0x60/0xe8
> [   79.033588]  el0_svc_handler+0x2c/0x80
> [   79.037327]  el0_svc+0x8/0xc
> [   79.040200] Code: 6b01005f 54fff788 940169b1 f9000320 (b9400801)
> [   79.046283] ---[ end trace 74db007d069c1cf7 ]---
> 
> Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
> Fixes: d829e9c4112b ("tls: convert to generic sk_msg interface")

Seems we only checked it upfront not as pages were being added. Thanks!

Acked-by: John Fastabend <john.fastabend@gmail.com>