Commit 81be3dee authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds

fs/xattr.c: zero out memory copied to userspace in getxattr

getxattr uses vmalloc to allocate memory if kzalloc fails.  This is
filled by vfs_getxattr and then copied to the userspace.  vmalloc,
however, doesn't zero out the memory so if the specific implementation
of the xattr handler is sloppy we can theoretically expose a kernel
memory.  There is no real sign this is really the case but let's make
sure this will not happen and use vzalloc instead.

Fixes: 779302e6 ("fs/xattr.c:getxattr(): improve handling of allocation failures")
Link: http://lkml.kernel.org/r/20170306103327.2766-1-mhocko@kernel.orgAcked-by: default avatarKees Cook <keescook@chromium.org>
Reported-by: default avatarVlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>	[3.6+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 847f716f
...@@ -530,7 +530,7 @@ getxattr(struct dentry *d, const char __user *name, void __user *value, ...@@ -530,7 +530,7 @@ getxattr(struct dentry *d, const char __user *name, void __user *value,
size = XATTR_SIZE_MAX; size = XATTR_SIZE_MAX;
kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); kvalue = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
if (!kvalue) { if (!kvalue) {
kvalue = vmalloc(size); kvalue = vzalloc(size);
if (!kvalue) if (!kvalue)
return -ENOMEM; return -ENOMEM;
} }
......
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