mirrors/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-12-27 11:06:41 -05:00
Code Issues Packages Projects Releases Wiki Activity

iommupt: Fix unlikely flows in increase_top()

Browse Source 
Since increase_top() does it's own READ_ONCE() on top_of_table, the
caller's prior READ_ONCE() could be inconsistent and the first time
through the loop we may actually already have the right level if two
threads are racing map.

In this case new_level will be left uninitialized.

Further all the exits from the loop have to either commit to the new top
or free any memory allocated so the early return must be a goto err_free.

Make it so the only break from the loop always sets new_level to the right
value and all other exits go to err_free. Use pts.level (the pts
represents the top we are stacking) within the loop instead of new_level.

Fixes: dcd6a011a8 ("iommupt: Add map_pages op")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/aRwgNW9PiW2j-Qwo@stanley.mountain
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Jason Gunthorpe
2025-11-20 14:47:42 -04:00
committed by Joerg Roedel
parent 1e8b6eb141
commit 152c862c17
1 changed files with 11 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/iommu/generic_pt/iommu_pt.h
View File

@@ -683,8 +683,11 @@ static int increase_top(struct pt_iommu *iommu_table, struct pt_range *range,
top_range.va = range->va;
top_range.last_va = range->last_va;
if (!pt_check_range(&top_range) && map->leaf_level <= pts.level)
if (!pt_check_range(&top_range) &&
map->leaf_level <= pts.level) {
new_level = pts.level;
break;
}
pts.level++;
if (pts.level > PT_MAX_TOP_LEVEL ||
@@ -693,17 +696,18 @@ static int increase_top(struct pt_iommu *iommu_table, struct pt_range *range,
goto err_free;
}
new_level = pts.level;
table_mem =
table_alloc_top(common, _pt_top_set(NULL, pts.level),
map->attrs.gfp, ALLOC_DEFER_COHERENT_FLUSH);
if (IS_ERR(table_mem))
return PTR_ERR(table_mem);
if (IS_ERR(table_mem)) {
ret = PTR_ERR(table_mem);
goto err_free;
}
iommu_pages_list_add(&free_list, table_mem);
/* The new table links to the lower table always at index 0 */
top_range.va = 0;
top_range.top_level = new_level;
top_range.top_level = pts.level;
pts.table_lower = pts.table;
pts.table = table_mem;
pt_load_single_entry(&pts);
@@ -735,7 +739,8 @@ static int increase_top(struct pt_iommu *iommu_table, struct pt_range *range,
*/
domain_lock = iommu_table->driver_ops->get_top_lock(iommu_table);
spin_lock_irqsave(domain_lock, flags);
if (common->top_of_table != top_of_table) {
if (common->top_of_table != top_of_table ||
top_of_table == new_top_of_table) {
spin_unlock_irqrestore(domain_lock, flags);
ret = -EAGAIN;
goto err_free;