asgardius/android_kernel_motorola_sm6225
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dma-buf: fix sleep-while-atomic in dmabuffs_dname

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There is a sleep-while-atomic reported when the selinux tries to
dump the file path name of a dmabuf file using d_path(). Fix it.
Flow will be like below:
flush_unauthorized_files -->
  iterate_fd -->
    spin_lock --> Start of the atomic section
      match_file -->
        file_has_perm -->
          avc_has_perm -->
            avc_audit -->
              slow_avc_audit -->
	        common_lsm_audit -->
		  dump_common_audit_data -->
		    audit_log_d_path -->
		      d_path -->
                        dmabuffs_dname -->
                          mutex_lock--> Sleep while atomic.

Change-Id: Ieed88a9093355d160e1c194d31fe33f1c7dadf60
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
This commit is contained in:
Charan Teja Reddy 2020-05-18 10:48:50 +05:30
parent 49f043455b
commit 15ff230bc5
2 changed files with 8 additions and 4 deletions
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11
drivers/dma-buf/dma-buf.c
View file

@ -92,10 +92,10 @@ static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
goto out;
}
spin_unlock(&dentry->d_lock);
mutex_lock(&dmabuf->lock);
spin_lock(&dmabuf->name_lock);
if (dmabuf->name)
ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN);
mutex_unlock(&dmabuf->lock);
spin_unlock(&dmabuf->name_lock);
dmabuf_dent_put(dmabuf);
out:
return dynamic_dname(dentry, buffer, buflen, "/%s:%s",
@ -401,8 +401,10 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
kfree(name);
goto out_unlock;
}
spin_lock(&dmabuf->name_lock);
kfree(dmabuf->name);
dmabuf->name = name;
spin_unlock(&dmabuf->name_lock);
out_unlock:
mutex_unlock(&dmabuf->lock);
@ -472,10 +474,10 @@ static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
/* Don't count the temporary reference taken inside procfs seq_show */
seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
mutex_lock(&dmabuf->lock);
spin_lock(&dmabuf->name_lock);
if (dmabuf->name)
seq_printf(m, "name:\t%s\n", dmabuf->name);
mutex_unlock(&dmabuf->lock);
spin_unlock(&dmabuf->name_lock);
}
static const struct file_operations dma_buf_fops = {
@ -619,6 +621,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
dmabuf->size = exp_info->size;
dmabuf->exp_name = exp_info->exp_name;
dmabuf->owner = exp_info->owner;
spin_lock_init(&dmabuf->name_lock);
init_waitqueue_head(&dmabuf->poll);
dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll;
dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0;

1
include/linux/dma-buf.h
View file

@ -427,6 +427,7 @@ struct dma_buf {
char *buf_name;
ktime_t ktime;
const char *name;
spinlock_t name_lock;
struct module *owner;
struct list_head list_node;
void *priv;