On Tue, Apr 5, 2022 at 10:24 AM David Wysochanski <dwysocha@xxxxxxxxxx> wrote:
>
> On Tue, Apr 5, 2022 at 10:14 AM David Howells <dhowells@xxxxxxxxxx> wrote:
> >
> > Dave Wysochanski <dwysocha@xxxxxxxxxx> wrote:
> >
> > > @@ -203,7 +203,7 @@ bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
> > > if (!buf)
> > > return false;
> > > buf->reserved = cpu_to_be32(0);
> > > - memcpy(buf->data, p, len);
> > > + memcpy(buf->data, p, volume->vcookie->coherency_len);
> >
> > Good catch. However, I think it's probably better to change things a bit
> > further up, eg.:
> >
> > - len += sizeof(*buf);
> > - buf = kmalloc(len, GFP_KERNEL);
> > + buf = kmalloc(sizeof(*buf) + len, GFP_KERNEL);
> >
> > David
> >
>
> Agree with the above. I'll send a v2. Thanks!
After I looked at this again I realized 'len' is used in
vfs_setxattr() and needs to be the size of the kmalloc'd memory.
So we need another adjustment there or the v1 patch.
191 bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
192 {
193 struct cachefiles_vol_xattr *buf;
194 unsigned int len = volume->vcookie->coherency_len;
195 const void *p = volume->vcookie->coherency;
196 struct dentry *dentry = volume->dentry;
197 int ret;
198
199 _enter("%x,#%d", volume->vcookie->debug_id, len);
200
201 buf = kmalloc(sizeof(*buf) + len, GFP_KERNEL);
202 if (!buf)
203 return false;
204 buf->reserved = cpu_to_be32(0);
205 memcpy(buf->data, p, len);
206
207 ret = cachefiles_inject_write_error();
208 if (ret == 0)
209 ret = vfs_setxattr(&init_user_ns, dentry,
cachefiles_xattr_cache,
210 buf, len, 0);
--
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