From: Krzysztof Grzywocz <kgrzywocz@xxxxx> Problem: On 64bit kernel ELF32bit gets improper value of `SCTP_GET_ASSOC_STATS` (call `getsockopt` on SCTP socket) due to different `struct sctp_assoc_stats` aligment (mostly because of different `_K_SS_ALIGNSIZE`). Example: Sent 1000 bytes, Received 1000 bytes May result in: packets sent(sas_opackets): 12884901888 packets recv(sas_ipackets): 12884901888 Patch solution: Realign struct at the end of `sctp_getsockopt_assoc_stats(..)` when called in compat mode see patch for details. For detail see: https://github.com/kgrzywocz/align_compat32_sctp_assoc_stats Signed-off-by: Krzysztof Grzywocz <kgrzywocz@xxxxx> ----- diff --git a/net/sctp/socket.c b/net/sctp/socket.c index ce620e87..4e3f920f 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -6685,6 +6685,59 @@ static int sctp_getsockopt_paddr_thresholds(struct sock *sk, return 0; } +#ifdef CONFIG_COMPAT + +struct __kernel_sockaddr_storage_compat32 { + __kernel_sa_family_t ss_family; + char __data[_K_SS_MAXSIZE - sizeof(unsigned short)]; +} __attribute__ ((packed,aligned(4))); /* force desired alignment */ + +struct sctp_assoc_stats_compat32 { + int32_t sas_assoc_id; + struct __kernel_sockaddr_storage_compat32 sas_obs_rto_ipaddr; + uint64_t sas_maxrto; + uint64_t sas_isacks; + uint64_t sas_osacks; + uint64_t sas_opackets; + uint64_t sas_ipackets; + uint64_t sas_rtxchunks; + uint64_t sas_outofseqtsns; + uint64_t sas_idupchunks; + uint64_t sas_gapcnt; + uint64_t sas_ouodchunks; + uint64_t sas_iuodchunks; + uint64_t sas_oodchunks; + uint64_t sas_iodchunks; + uint64_t sas_octrlchunks; + uint64_t sas_ictrlchunks; +} __attribute__ ((packed,aligned(4))); + +static void align_compat32_sctp_assoc_stats(void *sctp_assoc_stats) +{ + struct sctp_assoc_stats* p64 = sctp_assoc_stats; + struct sctp_assoc_stats_compat32* p32 = sctp_assoc_stats; + + p32->sas_assoc_id = p64->sas_assoc_id; + p32->sas_obs_rto_ipaddr.ss_family = p64->sas_obs_rto_ipaddr.ss_family; + memcpy(p32->sas_obs_rto_ipaddr.__data, p64->sas_obs_rto_ipaddr.__data, sizeof(p32->sas_obs_rto_ipaddr.__data)); + p32->sas_maxrto = p64->sas_maxrto; + p32->sas_isacks = p64->sas_isacks; + p32->sas_osacks = p64->sas_osacks; + p32->sas_opackets = p64->sas_opackets; + p32->sas_ipackets = p64->sas_ipackets; + p32->sas_rtxchunks = p64->sas_rtxchunks; + p32->sas_outofseqtsns = p64->sas_outofseqtsns; + p32->sas_idupchunks = p64->sas_idupchunks; + p32->sas_gapcnt = p64->sas_gapcnt; + p32->sas_ouodchunks = p64->sas_ouodchunks; + p32->sas_iuodchunks = p64->sas_iuodchunks; + p32->sas_oodchunks = p64->sas_oodchunks; + p32->sas_iodchunks = p64->sas_iodchunks; + p32->sas_octrlchunks = p64->sas_octrlchunks; + p32->sas_ictrlchunks = p64->sas_ictrlchunks; +} +#endif + /* * SCTP_GET_ASSOC_STATS * @@ -6743,6 +6796,13 @@ static int sctp_getsockopt_assoc_stats(struct sock *sk, int len, pr_debug("%s: len:%d, assoc_id:%d\n", __func__, len, sas.sas_assoc_id); +#ifdef CONFIG_COMPAT + if (in_compat_syscall()) { + pr_debug("%s: Aligning sctp_assoc_stats for 32bit compat\n", __func__); + align_compat32_sctp_assoc_stats(&sas); + } +#endif + if (copy_to_user(optval, &sas, len)) return -EFAULT;
