3.16.70-rc1 review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit ecd182cbf4e107928077866399100228d2359c60 upstream.
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@I-love.SAKURA.ne.jp Reviewed-by: Joel Fernandes joel@joelfernandes.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/staging/android/ashmem.c | 42 ++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 18 deletions(-)
--- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -158,19 +158,15 @@ static inline void lru_del(struct ashmem * @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 (unlikely(!range)) - return -ENOMEM; + struct ashmem_range *range = *new_range;
+ *new_range = NULL; range->asma = asma; range->pgstart = start; range->pgend = end; @@ -180,8 +176,6 @@ static int range_alloc(struct ashmem_are
if (range_on_lru(range)) lru_add(range); - - return 0; }
/** @@ -576,7 +570,8 @@ static int get_name(struct ashmem_area * * * 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; @@ -628,7 +623,7 @@ static int ashmem_pin(struct ashmem_area * 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; } @@ -642,7 +637,8 @@ static int ashmem_pin(struct ashmem_area * * 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; @@ -668,7 +664,8 @@ restart: } }
- return range_alloc(asma, range, purged, pgstart, pgend); + range_alloc(asma, range, purged, pgstart, pgend, new_range); + return 0; }
/* @@ -701,10 +698,17 @@ static int ashmem_pin_unpin(struct ashme struct ashmem_pin pin; size_t pgstart, pgend; int ret = -EINVAL; + struct ashmem_range *range = NULL;
if (unlikely(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);
if (unlikely(!asma->file)) @@ -728,10 +732,10 @@ static int ashmem_pin_unpin(struct ashme
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); @@ -740,6 +744,8 @@ static int ashmem_pin_unpin(struct ashme
out_unlock: mutex_unlock(&ashmem_mutex); + if (range) + kmem_cache_free(ashmem_range_cachep, range);
return ret; }