Since the allocation was being done throug memdup_user, the caller
is wrongly traced as being strndup_user (the correct trace should
report the caller of strndup_user).
This is a common problem: in order to get accurate callsite tracing,
a utils function can't allocate through another utils function,
but instead do the allocation himself.
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Ezequiel Garcia <elezegarcia@xxxxxxxxx>
---
I'm not sure this is the best solution,
but creating another function to reuse between strndup_user
and memdup_user seemed like an overkill.
mm/util.c | 15 ++++++++++++---
1 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/mm/util.c b/mm/util.c
index dc3036c..87ff667 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -214,10 +214,19 @@ char *strndup_user(const char __user *s, long n)
if (length > n)
return ERR_PTR(-EINVAL);
- p = memdup_user(s, length);
+ /*
+ * Always use GFP_KERNEL, since copy_from_user() can sleep and
+ * cause pagefault, which makes it pointless to use GFP_NOFS
+ * or GFP_ATOMIC.
+ */
+ p = kmalloc_track_caller(length, GFP_KERNEL);
+ if (!p)
+ return ERR_PTR(-ENOMEM);
- if (IS_ERR(p))
- return p;
+ if (copy_from_user(p, s, length)) {
+ kfree(p);
+ return ERR_PTR(-EFAULT);
+ }
p[length - 1] = '\0';
--
1.7.8.6
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