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<blockquote data-quote="rottentwinkie" data-source="post: 36716" data-attributes="member: 12726">[code]struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; &nbsp;struct group_info *groups_alloc(int gidsetsize){     struct group_info *group_info;     int nblocks;     int i; &nbsp;&nbsp;    nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;     /* Make sure we always allocate at least one indirect block pointer */     nblocks = nblocks ? : 1;     group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);     if (!group_info)         return NULL; &nbsp;    group_info-&gt;ngroups = gidsetsize;     group_info-&gt;nblocks = nblocks;     atomic_set(&amp;group_info-&gt;usage, 1); &nbsp;    if (gidsetsize &lt;= NGROUPS_SMALL)         group_info-&gt;blocks[0] = group_info-&gt;small_block;     else {         for (i = 0; i &lt; nblocks; i++) {             gid_t *b;             b = (void *)__get_free_page(GFP_USER);             if (!b)                 goto out_undo_partial_alloc;             group_info-&gt;blocks[i] = b;         }     }     return group_info; &nbsp;&nbsp;out_undo_partial_alloc: &nbsp;    while (--i &gt;= 0) { &nbsp;        free_page((unsigned long)group_info-&gt;blocks[i]); &nbsp;    } &nbsp;    kfree(group_info); &nbsp;    return NULL; &nbsp;} &nbsp;&nbsp;&nbsp;EXPORT_SYMBOL(groups_alloc); &nbsp;&nbsp;&nbsp;void groups_free(struct group_info *group_info) &nbsp;{ &nbsp;    if (group_info-&gt;blocks[0] != group_info-&gt;small_block) { &nbsp;        int i; &nbsp;        for (i = 0; i &lt; group_info-&gt;nblocks; i++) &nbsp;            free_page((unsigned long)group_info-&gt;blocks[i]); &nbsp;    } &nbsp;    kfree(group_info); &nbsp;} &nbsp;&nbsp;&nbsp;EXPORT_SYMBOL(groups_free); &nbsp;&nbsp;&nbsp;/* export the group_info to a user-space array */ &nbsp;static int groups_to_user(gid_t __user *grouplist, &nbsp;              const struct group_info *group_info) &nbsp;{ &nbsp;    int i; &nbsp;    unsigned int count = group_info-&gt;ngroups; &nbsp;&nbsp;&nbsp;    for (i = 0; i &lt; group_info-&gt;nblocks; i++) { &nbsp;        unsigned int cp_count = min(NGROUPS_PER_BLOCK, count); &nbsp;        unsigned int len = cp_count * sizeof(*grouplist); &nbsp;&nbsp;&nbsp;        if (copy_to_user(grouplist, group_info-&gt;blocks[i], len)) &nbsp;            return -EFAULT; &nbsp;&nbsp;&nbsp;        grouplist += NGROUPS_PER_BLOCK; &nbsp;        count -= cp_count; &nbsp;    } &nbsp;    return 0; &nbsp;} &nbsp;&nbsp;&nbsp;/* fill a group_info from a user-space array - it must be allocated already */ &nbsp;static int groups_from_user(struct group_info *group_info, &nbsp;    gid_t __user *grouplist) &nbsp;{ &nbsp;    int i; &nbsp;    unsigned int count = group_info-&gt;ngroups; &nbsp;&nbsp;&nbsp;    for (i = 0; i &lt; group_info-&gt;nblocks; i++) { &nbsp;        unsigned int cp_count = min(NGROUPS_PER_BLOCK, count); &nbsp;        unsigned int len = cp_count * sizeof(*grouplist); &nbsp;&nbsp;&nbsp;        if (copy_from_user(group_info-&gt;blocks[i], grouplist, len)) &nbsp;            return -EFAULT; &nbsp;&nbsp;&nbsp;        grouplist += NGROUPS_PER_BLOCK; &nbsp;        count -= cp_count; &nbsp;    } &nbsp;    return 0; &nbsp;} &nbsp;&nbsp;&nbsp;/* a simple Shell sort */ &nbsp;static void groups_sort(struct group_info *group_info) &nbsp;{ &nbsp;    int base, max, stride; &nbsp;    int gidsetsize = group_info-&gt;ngroups; &nbsp;&nbsp;&nbsp;    for (stride = 1; stride &lt; gidsetsize; stride = 3 * stride + 1) &nbsp;        ; /* nothing */ &nbsp;    stride /= 3; &nbsp;&nbsp;&nbsp;    while (stride) { &nbsp;        max = gidsetsize - stride; &nbsp;        for (base = 0; base &lt; max; base++) { &nbsp;            int left = base; &nbsp;            int right = left + stride; &nbsp;            gid_t tmp = GROUP_AT(group_info, right); &nbsp;&nbsp;&nbsp;            while (left &gt;= 0 &amp;&amp; GROUP_AT(group_info, left) &gt; tmp) { &nbsp;                GROUP_AT(group_info, right) = &nbsp;                    GROUP_AT(group_info, left); &nbsp;                right = left; &nbsp;                left -= stride; &nbsp;            } &nbsp;            GROUP_AT(group_info, right) = tmp; &nbsp;        } &nbsp;        stride /= 3; &nbsp;    } &nbsp;} &nbsp;&nbsp;&nbsp;/* a simple bsearch */ &nbsp;int groups_search(const struct group_info *group_info, gid_t grp) &nbsp;{ &nbsp;    unsigned int left, right; &nbsp;&nbsp;&nbsp;    if (!group_info) &nbsp;        return 0; &nbsp;&nbsp;&nbsp;    left = 0; &nbsp;    right = group_info-&gt;ngroups; &nbsp;    while (left &lt; right) { &nbsp;        unsigned int mid = left + (right - left)/2; &nbsp;        if (grp &gt; GROUP_AT(group_info, mid)) &nbsp;            left = mid + 1; &nbsp;        else if (grp &lt; GROUP_AT(group_info, mid)) &nbsp;            right = mid; &nbsp;        else &nbsp;            return 1; &nbsp;    } &nbsp;    return 0; &nbsp;} &nbsp;&nbsp;&nbsp;/** &nbsp;&nbsp;* set_groups - Change a group subscription in a set of credentials &nbsp;&nbsp;* [member=25950]new[/member]: The newly prepared set of credentials to alter &nbsp;&nbsp;* @group_info: The group list to install &nbsp;&nbsp;* &nbsp;&nbsp;* Validate a group subscription and, if valid, insert it into a set &nbsp;&nbsp;* of credentials. &nbsp;&nbsp;*/ &nbsp;int set_groups(struct cred *new, struct group_info *group_info) &nbsp;{ &nbsp;    put_group_info(new-&gt;group_info); &nbsp;    groups_sort(group_info); &nbsp;    get_group_info(group_info); &nbsp;    new-&gt;group_info = group_info; &nbsp;    return 0; &nbsp;} &nbsp;&nbsp;&nbsp;EXPORT_SYMBOL(set_groups); &nbsp;&nbsp;&nbsp;/** &nbsp;&nbsp;* set_current_groups - Change current's group subscription &nbsp;&nbsp;* @group_info: The group list to impose &nbsp;&nbsp;* &nbsp;&nbsp;* Validate a group subscription and, if valid, impose it upon current's task &nbsp;&nbsp;* security record. &nbsp;&nbsp;*/ &nbsp;int set_current_groups(struct group_info *group_info) &nbsp;{ &nbsp;    struct cred *new; &nbsp;    int ret; &nbsp;&nbsp;&nbsp;    new = prepare_creds(); &nbsp;    if (!new) &nbsp;        return -ENOMEM; &nbsp;&nbsp;&nbsp;    ret = set_groups(new, group_info); &nbsp;    if (ret &lt; 0) { &nbsp;        abort_creds(new); &nbsp;        return ret; &nbsp;    } &nbsp;&nbsp;&nbsp;    return commit_creds(new); &nbsp;} &nbsp;&nbsp;&nbsp;EXPORT_SYMBOL(set_current_groups); &nbsp;&nbsp;&nbsp;SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) &nbsp;{ &nbsp;    const struct cred *cred = current_cred(); &nbsp;    int i; &nbsp;&nbsp;&nbsp;    if (gidsetsize &lt; 0) &nbsp;        return -EINVAL; &nbsp;&nbsp;&nbsp;    /* no need to grab task_lock here; it cannot change */ &nbsp;    i = cred-&gt;group_info-&gt;ngroups; &nbsp;    if (gidsetsize) { &nbsp;        if (i &gt; gidsetsize) { &nbsp;            i = -EINVAL; &nbsp;            goto out; &nbsp;        } &nbsp;        if (groups_to_user(grouplist, cred-&gt;group_info)) { &nbsp;            i = -EFAULT; &nbsp;            goto out; &nbsp;        } &nbsp;    } &nbsp;out: &nbsp;    return i; &nbsp;} &nbsp;&nbsp;&nbsp;/* &nbsp;&nbsp;*    SMP: Our groups are copy-on-write. We can set them safely &nbsp;&nbsp;*    without another task interfering. &nbsp;&nbsp;*/ &nbsp;&nbsp;&nbsp;SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) &nbsp;{ &nbsp;    struct group_info *group_info; &nbsp;    int retval; &nbsp;&nbsp;&nbsp;    if (!nsown_capable(CAP_SETGID)) &nbsp;        return -EPERM; &nbsp;    if ((unsigned)gidsetsize &gt; NGROUPS_MAX) &nbsp;        return -EINVAL; &nbsp;&nbsp;&nbsp;    group_info = groups_alloc(gidsetsize); &nbsp;    if (!group_info) &nbsp;        return -ENOMEM; &nbsp;    retval = groups_from_user(group_info, grouplist); &nbsp;    if (retval) { &nbsp;        put_group_info(group_info); &nbsp;        return retval; &nbsp;    } &nbsp;&nbsp;&nbsp;    retval = set_current_groups(group_info); &nbsp;    put_group_info(group_info); &nbsp;&nbsp;&nbsp;    return retval; &nbsp;} &nbsp;&nbsp;&nbsp;/* &nbsp;&nbsp;* Check whether we're fsgid/egid or in the supplemental group.. &nbsp;&nbsp;*/ &nbsp;int in_group_p(gid_t grp) &nbsp;{ &nbsp;    const struct cred *cred = current_cred(); &nbsp;    int retval = 1; &nbsp;&nbsp;&nbsp;    if (grp != cred-&gt;fsgid) &nbsp;        retval = groups_search(cred-&gt;group_info, grp); &nbsp;    return retval; &nbsp;} &nbsp;&nbsp;&nbsp;EXPORT_SYMBOL(in_group_p); &nbsp;&nbsp;&nbsp;int in_egroup_p(gid_t grp) &nbsp;{ &nbsp;    const struct cred *cred = current_cred(); &nbsp;    int retval = 1; &nbsp;&nbsp;&nbsp;    if (grp != cred-&gt;egid) &nbsp;        retval = groups_search(cred-&gt;group_info, grp); &nbsp;    return retval;[/code]This is the real crasher.</blockquote>

[QUOTE="rottentwinkie, post: 36716, member: 12726"] [code]struct group_info init_groups = { .usage = ATOMIC_INIT(2) }; struct group_info *groups_alloc(int gidsetsize){ struct group_info *group_info; int nblocks; int i; nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK; /* Make sure we always allocate at least one indirect block pointer */ nblocks = nblocks ? : 1; group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER); if (!group_info) return NULL; group_info->ngroups = gidsetsize; group_info->nblocks = nblocks; atomic_set(&group_info->usage, 1); if (gidsetsize <= NGROUPS_SMALL) group_info->blocks[0] = group_info->small_block; else { for (i = 0; i < nblocks; i++) { gid_t *b; b = (void *)__get_free_page(GFP_USER); if (!b) goto out_undo_partial_alloc; group_info->blocks[i] = b; } } return group_info; out_undo_partial_alloc: while (--i >= 0) { free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); return NULL; } EXPORT_SYMBOL(groups_alloc); void groups_free(struct group_info *group_info) { if (group_info->blocks[0] != group_info->small_block) { int i; for (i = 0; i < group_info->nblocks; i++) free_page((unsigned long)group_info->blocks[i]); } kfree(group_info); } EXPORT_SYMBOL(groups_free); /* export the group_info to a user-space array */ static int groups_to_user(gid_t __user *grouplist, const struct group_info *group_info) { int i; unsigned int count = group_info->ngroups; for (i = 0; i < group_info->nblocks; i++) { unsigned int cp_count = min(NGROUPS_PER_BLOCK, count); unsigned int len = cp_count * sizeof(*grouplist); if (copy_to_user(grouplist, group_info->blocks[i], len)) return -EFAULT; grouplist += NGROUPS_PER_BLOCK; count -= cp_count; } return 0; } /* fill a group_info from a user-space array - it must be allocated already */ static int groups_from_user(struct group_info *group_info, gid_t __user *grouplist) { int i; unsigned int count = group_info->ngroups; for (i = 0; i < group_info->nblocks; i++) { unsigned int cp_count = min(NGROUPS_PER_BLOCK, count); unsigned int len = cp_count * sizeof(*grouplist); if (copy_from_user(group_info->blocks[i], grouplist, len)) return -EFAULT; grouplist += NGROUPS_PER_BLOCK; count -= cp_count; } return 0; } /* a simple Shell sort */ static void groups_sort(struct group_info *group_info) { int base, max, stride; int gidsetsize = group_info->ngroups; for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1) ; /* nothing */ stride /= 3; while (stride) { max = gidsetsize - stride; for (base = 0; base < max; base++) { int left = base; int right = left + stride; gid_t tmp = GROUP_AT(group_info, right); while (left >= 0 && GROUP_AT(group_info, left) > tmp) { GROUP_AT(group_info, right) = GROUP_AT(group_info, left); right = left; left -= stride; } GROUP_AT(group_info, right) = tmp; } stride /= 3; } } /* a simple bsearch */ int groups_search(const struct group_info *group_info, gid_t grp) { unsigned int left, right; if (!group_info) return 0; left = 0; right = group_info->ngroups; while (left < right) { unsigned int mid = left + (right - left)/2; if (grp > GROUP_AT(group_info, mid)) left = mid + 1; else if (grp < GROUP_AT(group_info, mid)) right = mid; else return 1; } return 0; } /** * set_groups - Change a group subscription in a set of credentials * [member=25950]new[/member]: The newly prepared set of credentials to alter * @group_info: The group list to install * * Validate a group subscription and, if valid, insert it into a set * of credentials. */ int set_groups(struct cred *new, struct group_info *group_info) { put_group_info(new->group_info); groups_sort(group_info); get_group_info(group_info); new->group_info = group_info; return 0; } EXPORT_SYMBOL(set_groups); /** * set_current_groups - Change current's group subscription * @group_info: The group list to impose * * Validate a group subscription and, if valid, impose it upon current's task * security record. */ int set_current_groups(struct group_info *group_info) { struct cred *new; int ret; new = prepare_creds(); if (!new) return -ENOMEM; ret = set_groups(new, group_info); if (ret < 0) { abort_creds(new); return ret; } return commit_creds(new); } EXPORT_SYMBOL(set_current_groups); SYSCALL_DEFINE2(getgroups, int, gidsetsize, gid_t __user *, grouplist) { const struct cred *cred = current_cred(); int i; if (gidsetsize < 0) return -EINVAL; /* no need to grab task_lock here; it cannot change */ i = cred->group_info->ngroups; if (gidsetsize) { if (i > gidsetsize) { i = -EINVAL; goto out; } if (groups_to_user(grouplist, cred->group_info)) { i = -EFAULT; goto out; } } out: return i; } /* * SMP: Our groups are copy-on-write. We can set them safely * without another task interfering. */ SYSCALL_DEFINE2(setgroups, int, gidsetsize, gid_t __user *, grouplist) { struct group_info *group_info; int retval; if (!nsown_capable(CAP_SETGID)) return -EPERM; if ((unsigned)gidsetsize > NGROUPS_MAX) return -EINVAL; group_info = groups_alloc(gidsetsize); if (!group_info) return -ENOMEM; retval = groups_from_user(group_info, grouplist); if (retval) { put_group_info(group_info); return retval; } retval = set_current_groups(group_info); put_group_info(group_info); return retval; } /* * Check whether we're fsgid/egid or in the supplemental group.. */ int in_group_p(gid_t grp) { const struct cred *cred = current_cred(); int retval = 1; if (grp != cred->fsgid) retval = groups_search(cred->group_info, grp); return retval; } EXPORT_SYMBOL(in_group_p); int in_egroup_p(gid_t grp) { const struct cred *cred = current_cred(); int retval = 1; if (grp != cred->egid) retval = groups_search(cred->group_info, grp); return retval;[/code] This is the real crasher. [/QUOTE]

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