Commit 8c81ddd2 authored by Waiman Long's avatar Waiman Long Committed by Linus Torvalds

ipc: IPCMNI limit check for semmni

For SysV semaphores, the semmni value is the last part of the 4-element
sem number array.  To make semmni behave in a similar way to msgmni and
shmmni, we can't directly use the _minmax handler.  Instead, a special sem
specific handler is added to check the last argument to make sure that it
is limited to the [0, IPCMNI] range.  An error will be returned if this is
not the case.

Link: Waiman Long's avatarWaiman Long <>
Reviewed-by: 's avatarDavidlohr Bueso <>
Cc: "Eric W. Biederman" <>
Cc: Jonathan Corbet <>
Cc: Kees Cook <>
Cc: Luis R. Rodriguez <>
Cc: Matthew Wilcox <>
Cc: Takashi Iwai <>
Signed-off-by: 's avatarAndrew Morton <>
Signed-off-by: 's avatarLinus Torvalds <>
parent 6730e658
......@@ -88,12 +88,33 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write,
return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
static int proc_ipc_sem_dointvec(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
int ret, semmni;
struct ipc_namespace *ns = current->nsproxy->ipc_ns;
semmni = ns->sem_ctls[3];
ret = proc_ipc_dointvec(table, write, buffer, lenp, ppos);
if (!ret)
ret = sem_check_semmni(current->nsproxy->ipc_ns);
* Reset the semmni value if an error happens.
if (ret)
ns->sem_ctls[3] = semmni;
return ret;
#define proc_ipc_doulongvec_minmax NULL
#define proc_ipc_dointvec NULL
#define proc_ipc_dointvec_minmax NULL
#define proc_ipc_dointvec_minmax_orphans NULL
#define proc_ipc_auto_msgmni NULL
#define proc_ipc_sem_dointvec NULL
static int zero;
......@@ -175,7 +196,7 @@ static struct ctl_table ipc_kern_table[] = {
.data = &init_ipc_ns.sem_ctls,
.maxlen = 4*sizeof(int),
.mode = 0644,
.proc_handler = proc_ipc_dointvec,
.proc_handler = proc_ipc_sem_dointvec,
......@@ -217,6 +217,15 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
static inline int sem_check_semmni(struct ipc_namespace *ns) {
* Check semmni range [0, IPCMNI]
* semmni is the last element of sem_ctls[4] array
return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > IPCMNI))
? -ERANGE : 0;
#include <linux/compat.h>
struct compat_ipc_perm {
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