@@ -497,8 +497,9 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
struct ib_umad_packet *packet;
struct ib_mad_agent *agent;
struct rdma_ah_attr ah_attr;
+ struct ib_rmpp_hdr rmpp_hdr;
+ struct ib_mad_hdr mad_hdr;
struct ib_ah *ah;
- struct ib_rmpp_mad *rmpp_mad;
__be64 *tid;
int ret, data_len, hdr_len, copy_offset, rmpp_active;
u8 base_version;
@@ -506,7 +507,7 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
if (count < hdr_size(file) + IB_MGMT_RMPP_HDR)
return -EINVAL;
- packet = kzalloc(sizeof *packet + IB_MGMT_RMPP_HDR, GFP_KERNEL);
+ packet = kzalloc(sizeof(*packet) + IB_MGMT_RMPP_HDR, GFP_KERNEL);
if (!packet)
return -ENOMEM;
@@ -560,13 +561,14 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
goto err_up;
}
- rmpp_mad = (struct ib_rmpp_mad *) packet->mad.data;
- hdr_len = ib_get_mad_data_offset(rmpp_mad->mad_hdr.mgmt_class);
+ mad_hdr = *(struct ib_mad_hdr *)packet->mad.data;
+ rmpp_hdr = *(struct ib_rmpp_hdr *)((u8 *)packet->mad.data + sizeof(struct ib_mad_hdr));
+ hdr_len = ib_get_mad_data_offset(mad_hdr.mgmt_class);
- if (ib_is_mad_class_rmpp(rmpp_mad->mad_hdr.mgmt_class)
+ if (ib_is_mad_class_rmpp(mad_hdr.mgmt_class)
&& ib_mad_kernel_rmpp_agent(agent)) {
copy_offset = IB_MGMT_RMPP_HDR;
- rmpp_active = ib_get_rmpp_flags(&rmpp_mad->rmpp_hdr) &
+ rmpp_active = ib_get_rmpp_flags(&rmpp_hdr) &
IB_MGMT_RMPP_FLAG_ACTIVE;
} else {
copy_offset = IB_MGMT_MAD_HDR;
@@ -615,12 +617,12 @@ static ssize_t ib_umad_write(struct file *filp, const char __user *buf,
tid = &((struct ib_mad_hdr *) packet->msg->mad)->tid;
*tid = cpu_to_be64(((u64) agent->hi_tid) << 32 |
(be64_to_cpup(tid) & 0xffffffff));
- rmpp_mad->mad_hdr.tid = *tid;
+ mad_hdr.tid = *tid;
}
if (!ib_mad_kernel_rmpp_agent(agent)
- && ib_is_mad_class_rmpp(rmpp_mad->mad_hdr.mgmt_class)
- && (ib_get_rmpp_flags(&rmpp_mad->rmpp_hdr) & IB_MGMT_RMPP_FLAG_ACTIVE)) {
+ && ib_is_mad_class_rmpp(mad_hdr.mgmt_class)
+ && (ib_get_rmpp_flags(&rmpp_hdr) & IB_MGMT_RMPP_FLAG_ACTIVE)) {
spin_lock_irq(&file->send_lock);
list_add_tail(&packet->list, &file->send_list);
spin_unlock_irq(&file->send_lock);
GCC-13 (and Clang)[1] does not like to access a partially allocated object, since it cannot reason about it for bounds checking. In this case 140 bytes are allocated for an object of type struct ib_umad_packet: packet = kzalloc(sizeof(*packet) + IB_MGMT_RMPP_HDR, GFP_KERNEL); However, notice that sizeof(*packet) is only 104 bytes: struct ib_umad_packet { struct ib_mad_send_buf * msg; /* 0 8 */ struct ib_mad_recv_wc * recv_wc; /* 8 8 */ struct list_head list; /* 16 16 */ int length; /* 32 4 */ /* XXX 4 bytes hole, try to pack */ struct ib_user_mad mad __attribute__((__aligned__(8))); /* 40 64 */ /* size: 104, cachelines: 2, members: 5 */ /* sum members: 100, holes: 1, sum holes: 4 */ /* forced alignments: 1, forced holes: 1, sum forced holes: 4 */ /* last cacheline: 40 bytes */ } __attribute__((__aligned__(8))); and 36 bytes extra bytes are allocated for a flexible-array member in struct ib_user_mad: include/rdma/ib_mad.h: 120 enum { ... 123 IB_MGMT_RMPP_HDR = 36, ... } struct ib_user_mad { struct ib_user_mad_hdr hdr; /* 0 64 */ /* --- cacheline 1 boundary (64 bytes) --- */ __u64 data[] __attribute__((__aligned__(8))); /* 64 0 */ /* size: 64, cachelines: 1, members: 2 */ /* forced alignments: 1 */ } __attribute__((__aligned__(8))); So we have sizeof(*packet) + IB_MGMT_RMPP_HDR == 140 bytes Then the address of the flex-array member (for which only 36 bytes were allocated) is casted and copied into a pointer to struct ib_rmpp_mad, which, in turn, is of size 256 bytes: rmpp_mad = (struct ib_rmpp_mad *) packet->mad.data; struct ib_rmpp_mad { struct ib_mad_hdr mad_hdr; /* 0 24 */ struct ib_rmpp_hdr rmpp_hdr; /* 24 12 */ u8 data[220]; /* 36 220 */ /* size: 256, cachelines: 4, members: 3 */ }; The thing is that those 36 bytes allocated for flex-array member data in struct ib_user_mad onlly account for the size of both struct ib_mad_hdr and struct ib_rmpp_hdr, but nothing is left for array u8 data[220]. So, the compiler is legitimately complaining about accessing an object for which not enough memory was allocated. Apparently, the only members of struct ib_rmpp_mad that are relevant (that are actually being used) in function ib_umad_write() are mad_hdr and rmpp_hdr. So, instead of casting packet->mad.data to (struct ib_rmpp_mad *) cast it just to the two members for which enough memory was allocated. That's actually the reason why IB_MGMT_RMPP_HDR == sizeof(struct ib_mad_hdr) + sizeof(struct ib_rmpp_hdr) == 36 bytes Refactor the rest of the code, accordingly. Fix the following warnings seen under GCC-13 and -Warray-bounds: drivers/infiniband/core/user_mad.c:564:50: warning: array subscript ‘struct ib_rmpp_mad[0]’ is partly outside array bounds of ‘unsigned char[140]’ [-Warray-bounds=] drivers/infiniband/core/user_mad.c:566:42: warning: array subscript ‘struct ib_rmpp_mad[0]’ is partly outside array bounds of ‘unsigned char[140]’ [-Warray-bounds=] drivers/infiniband/core/user_mad.c:618:25: warning: array subscript ‘struct ib_rmpp_mad[0]’ is partly outside array bounds of ‘unsigned char[140]’ [-Warray-bounds=] drivers/infiniband/core/user_mad.c:622:44: warning: array subscript ‘struct ib_rmpp_mad[0]’ is partly outside array bounds of ‘unsigned char[140]’ [-Warray-bounds=] Link: https://github.com/KSPP/linux/issues/273 Link: https://godbolt.org/z/oYWaGM4Yb [1] Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/infiniband/core/user_mad.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-)