diff options
author | Francesco Ruggeri <fruggeri@arista.com> | 2019-11-19 21:47:27 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-17 20:39:36 +0100 |
commit | 9c996bfa0802a7d69387efc27e16dacdaa4fa227 (patch) | |
tree | 047fb7d6a28adcecc7df08eaa4ef32fb3f0388b2 /drivers | |
parent | 6dd08f64d4aec82510820f9359b8e6d37ef61728 (diff) |
ACPI: OSL: only free map once in osl.c
commit 833a426cc471b6088011b3d67f1dc4e147614647 upstream.
acpi_os_map_cleanup checks map->refcount outside of acpi_ioremap_lock
before freeing the map. This creates a race condition the can result
in the map being freed more than once.
A panic can be caused by running
for ((i=0; i<10; i++))
do
for ((j=0; j<100000; j++))
do
cat /sys/firmware/acpi/tables/data/BERT >/dev/null
done &
done
This patch makes sure that only the process that drops the reference
to 0 does the freeing.
Fixes: b7c1fadd6c2e ("ACPI: Do not use krefs under a mutex in osl.c")
Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/acpi/osl.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index 9da7e7d874bd..ff36b0101ff0 100644 --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -371,19 +371,21 @@ void *__ref acpi_os_map_memory(acpi_physical_address phys, acpi_size size) } EXPORT_SYMBOL_GPL(acpi_os_map_memory); -static void acpi_os_drop_map_ref(struct acpi_ioremap *map) +/* Must be called with mutex_lock(&acpi_ioremap_lock) */ +static unsigned long acpi_os_drop_map_ref(struct acpi_ioremap *map) { - if (!--map->refcount) + unsigned long refcount = --map->refcount; + + if (!refcount) list_del_rcu(&map->list); + return refcount; } static void acpi_os_map_cleanup(struct acpi_ioremap *map) { - if (!map->refcount) { - synchronize_rcu_expedited(); - acpi_unmap(map->phys, map->virt); - kfree(map); - } + synchronize_rcu_expedited(); + acpi_unmap(map->phys, map->virt); + kfree(map); } /** @@ -403,6 +405,7 @@ static void acpi_os_map_cleanup(struct acpi_ioremap *map) void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size) { struct acpi_ioremap *map; + unsigned long refcount; if (!acpi_permanent_mmap) { __acpi_unmap_table(virt, size); @@ -416,10 +419,11 @@ void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size) WARN(true, PREFIX "%s: bad address %p\n", __func__, virt); return; } - acpi_os_drop_map_ref(map); + refcount = acpi_os_drop_map_ref(map); mutex_unlock(&acpi_ioremap_lock); - acpi_os_map_cleanup(map); + if (!refcount) + acpi_os_map_cleanup(map); } EXPORT_SYMBOL_GPL(acpi_os_unmap_iomem); @@ -454,6 +458,7 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas) { u64 addr; struct acpi_ioremap *map; + unsigned long refcount; if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) return; @@ -469,10 +474,11 @@ void acpi_os_unmap_generic_address(struct acpi_generic_address *gas) mutex_unlock(&acpi_ioremap_lock); return; } - acpi_os_drop_map_ref(map); + refcount = acpi_os_drop_map_ref(map); mutex_unlock(&acpi_ioremap_lock); - acpi_os_map_cleanup(map); + if (!refcount) + acpi_os_map_cleanup(map); } EXPORT_SYMBOL(acpi_os_unmap_generic_address); |