The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From ecd182cbf4e107928077866399100228d2359c60 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 22 Feb 2019 20:03:55 +0900
Subject: [PATCH] staging: android: ashmem: Avoid range_alloc() allocation with
ashmem_mutex held.
ashmem_pin() is calling range_shrink() without checking whether
range_alloc() succeeded. Also, doing memory allocation with ashmem_mutex
held should be avoided because ashmem_shrink_scan() tries to hold it.
Therefore, move memory allocation for range_alloc() to ashmem_pin_unpin()
and make range_alloc() not to fail.
This patch is mostly meant for backporting purpose for fuzz testing on
stable/distributor kernels, for there is a plan to remove this code in
near future.
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Reviewed-by: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 5d5b091b957a..74d497d39c5a 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -172,19 +172,15 @@ static inline void lru_del(struct ashmem_range *range)
* @end: The ending page (inclusive)
*
* This function is protected by ashmem_mutex.
- *
- * Return: 0 if successful, or -ENOMEM if there is an error
*/
-static int range_alloc(struct ashmem_area *asma,
- struct ashmem_range *prev_range, unsigned int purged,
- size_t start, size_t end)
+static void range_alloc(struct ashmem_area *asma,
+ struct ashmem_range *prev_range, unsigned int purged,
+ size_t start, size_t end,
+ struct ashmem_range **new_range)
{
- struct ashmem_range *range;
-
- range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
- if (!range)
- return -ENOMEM;
+ struct ashmem_range *range = *new_range;
+ *new_range = NULL;
range->asma = asma;
range->pgstart = start;
range->pgend = end;
@@ -194,8 +190,6 @@ static int range_alloc(struct ashmem_area *asma,
if (range_on_lru(range))
lru_add(range);
-
- return 0;
}
/**
@@ -597,7 +591,8 @@ static int get_name(struct ashmem_area *asma, void __user *name)
*
* Caller must hold ashmem_mutex.
*/
-static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
+static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend,
+ struct ashmem_range **new_range)
{
struct ashmem_range *range, *next;
int ret = ASHMEM_NOT_PURGED;
@@ -650,7 +645,7 @@ static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
* second half and adjust the first chunk's endpoint.
*/
range_alloc(asma, range, range->purged,
- pgend + 1, range->pgend);
+ pgend + 1, range->pgend, new_range);
range_shrink(range, range->pgstart, pgstart - 1);
break;
}
@@ -664,7 +659,8 @@ static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
*
* Caller must hold ashmem_mutex.
*/
-static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
+static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend,
+ struct ashmem_range **new_range)
{
struct ashmem_range *range, *next;
unsigned int purged = ASHMEM_NOT_PURGED;
@@ -690,7 +686,8 @@ static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
}
}
- return range_alloc(asma, range, purged, pgstart, pgend);
+ range_alloc(asma, range, purged, pgstart, pgend, new_range);
+ return 0;
}
/*
@@ -723,10 +720,17 @@ static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
struct ashmem_pin pin;
size_t pgstart, pgend;
int ret = -EINVAL;
+ struct ashmem_range *range = NULL;
if (copy_from_user(&pin, p, sizeof(pin)))
return -EFAULT;
+ if (cmd == ASHMEM_PIN || cmd == ASHMEM_UNPIN) {
+ range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
+ if (!range)
+ return -ENOMEM;
+ }
+
mutex_lock(&ashmem_mutex);
wait_event(ashmem_shrink_wait, !atomic_read(&ashmem_shrink_inflight));
@@ -751,10 +755,10 @@ static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
switch (cmd) {
case ASHMEM_PIN:
- ret = ashmem_pin(asma, pgstart, pgend);
+ ret = ashmem_pin(asma, pgstart, pgend, &range);
break;
case ASHMEM_UNPIN:
- ret = ashmem_unpin(asma, pgstart, pgend);
+ ret = ashmem_unpin(asma, pgstart, pgend, &range);
break;
case ASHMEM_GET_PIN_STATUS:
ret = ashmem_get_pin_status(asma, pgstart, pgend);
@@ -763,6 +767,8 @@ static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
out_unlock:
mutex_unlock(&ashmem_mutex);
+ if (range)
+ kmem_cache_free(ashmem_range_cachep, range);
return ret;
}
