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Fix, and an update, for the "ipcs" command. The fix addresses an

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error where IPCS entries are not displayed because of a faulty
read of the "deleted" member of the embedded "kern_ipc_perm" data
structure.  The "deleted" member was being read as a 4-byte integer,
but since it is declared as a "bool" type, only the lowest byte gets
set to 1 or 0.  Since the structure is not zeroed-out when allocated,
stale data may be left in the upper 3 bytes, and the IPCS entry
gets rejected.  The update is required for Linux 4.11 and greater
kernels, which reimplemented the IDR facility to use radix trees
in kernel commit 0a835c4f090af2c76fc2932c539c3b32fd21fbbb, titled
"Reimplement IDR and IDA using the radix tree".  Without the patch,
if any IPCS entry exists, the command would fail with the message
"ipcs: invalid structure member offset: idr_top"
(anderson@redhat.com)
This commit is contained in:
Dave Anderson 2018-04-30 10:38:26 -04:00
parent 48b1708609
commit 759dc0c50d
1 changed files with 49 additions and 14 deletions
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63
ipcs.c
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@ -71,6 +71,8 @@ struct ipcs_table {
ulong shm_f_op_huge_addr;
int use_shm_f_op;
int seq_multiplier;
int rt_cnt;
struct radix_tree_pair *rtp;
};
/*
@ -92,6 +94,7 @@ static void get_sem_info(struct sem_info *, ulong, int);
static void get_msg_info(struct msg_info *, ulong, int);
static void add_rss_swap(ulong, int, ulong *, ulong *);
static int is_file_hugepages(ulong);
static void gather_radix_tree_entries(ulong);
/*
* global data
@ -574,7 +577,7 @@ ipc_search_array(ulong ipc_ids_p, int specified, ulong specified_value, int (*fn
static int
ipc_search_idr(ulong ipc_ids_p, int specified, ulong specified_value, int (*fn)(ulong, int, ulong, int, int), int verbose)
{
int in_use;
int i, in_use;
ulong ipcs_idr_p;
ulong ipc;
int next_id, total;
@ -591,16 +594,32 @@ ipc_search_idr(ulong ipc_ids_p, int specified, ulong specified_value, int (*fn)(
return 0;
}
for (total = 0, next_id = 0; total < in_use; next_id++) {
ipc = idr_find(ipcs_idr_p, next_id);
if (ipc == 0)
continue;
total++;
if (fn(ipc, specified, specified_value, next_id, verbose)) {
found = 1;
if (specified != SPECIFIED_NOTHING)
break;
if (VALID_MEMBER(idr_idr_rt)) {
gather_radix_tree_entries(ipcs_idr_p);
for (i = 0; i < ipcs_table.rt_cnt; i++) {
ipc = (ulong)ipcs_table.rtp[i].value;
if (fn(ipc, specified, specified_value, UNUSED, verbose)) {
found = 1;
if (specified != SPECIFIED_NOTHING)
break;
}
}
if (ipcs_table.rtp)
FREEBUF(ipcs_table.rtp);
} else {
for (total = 0, next_id = 0; total < in_use; next_id++) {
ipc = idr_find(ipcs_idr_p, next_id);
if (ipc == 0)
continue;
total++;
if (fn(ipc, specified, specified_value, next_id, verbose)) {
found = 1;
if (specified != SPECIFIED_NOTHING)
break;
}
}
}
@ -885,7 +904,7 @@ get_shm_info(struct shm_info *shm_info, ulong shp, int id)
add_rss_swap(inodep, is_file_hugepages(filep), &shm_info->rss,
&shm_info->swap);
shm_info->deleted = UINT(buf + OFFSET(shmid_kernel_shm_perm) +
shm_info->deleted = UCHAR(buf + OFFSET(shmid_kernel_shm_perm) +
OFFSET(kern_ipc_perm_deleted));
}
@ -930,7 +949,7 @@ get_sem_info(struct sem_info *sem_info, ulong shp, int id)
sem_info->nsems = ULONG(buf + OFFSET(sem_array_sem_nsems));
sem_info->deleted = UINT(buf + OFFSET(sem_array_sem_perm) +
sem_info->deleted = UCHAR(buf + OFFSET(sem_array_sem_perm) +
OFFSET(kern_ipc_perm_deleted));
}
@ -976,7 +995,7 @@ get_msg_info(struct msg_info *msg_info, ulong shp, int id)
msg_info->messages = ULONG(buf + OFFSET(msg_queue_q_qnum));
msg_info->deleted = UINT(buf + OFFSET(msg_queue_q_perm) +
msg_info->deleted = UCHAR(buf + OFFSET(msg_queue_q_perm) +
OFFSET(kern_ipc_perm_deleted));
}
@ -1083,3 +1102,19 @@ again:
return 0;
}
static void
gather_radix_tree_entries(ulong ipcs_idr_p)
{
long len;
ipcs_table.rt_cnt = do_radix_tree(ipcs_idr_p, RADIX_TREE_COUNT, NULL);
if (ipcs_table.rt_cnt) {
len = sizeof(struct radix_tree_pair) * (ipcs_table.rt_cnt+1);
ipcs_table.rtp = (struct radix_tree_pair *)GETBUF(len);
ipcs_table.rtp[0].index = ipcs_table.rt_cnt;
ipcs_table.rt_cnt = do_radix_tree(ipcs_idr_p, RADIX_TREE_GATHER, ipcs_table.rtp);
} else
ipcs_table.rtp = NULL;
}