The check_object_size() checks under CONFIG_HARDENED_USERCOPY need to be more defensive against running from interrupt context. Use a best-effort check for VMAP areas when running in interrupt context Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx> Link: https://lore.kernel.org/linux-mm/YyQ2CSdIJdvQPSPO@xxxxxxxxxxxxxxxxxxxx Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Yu Zhao <yuzhao@xxxxxxxxxx> Cc: dev@xxxxxxxxxxx Cc: linux-mm@xxxxxxxxx Cc: linux-hardening@xxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- include/linux/vmalloc.h | 1 + mm/usercopy.c | 11 ++++++++++- mm/vmalloc.c | 11 +++++++++++ 3 files changed, 22 insertions(+), 1 deletion(-) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 096d48aa3437..c8a00f181a11 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -216,6 +216,7 @@ void free_vm_area(struct vm_struct *area); extern struct vm_struct *remove_vm_area(const void *addr); extern struct vm_struct *find_vm_area(const void *addr); struct vmap_area *find_vmap_area(unsigned long addr); +struct vmap_area *find_vmap_area_try(unsigned long addr); static inline bool is_vm_area_hugepages(const void *addr) { diff --git a/mm/usercopy.c b/mm/usercopy.c index c1ee15a98633..4a371099ac64 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -173,7 +173,16 @@ static inline void check_heap_object(const void *ptr, unsigned long n, } if (is_vmalloc_addr(ptr)) { - struct vmap_area *area = find_vmap_area(addr); + struct vmap_area *area; + + if (unlikely(in_interrupt())) { + area = find_vmap_area_try(addr); + /* Give up under interrupt to avoid deadlocks. */ + if (!area) + return; + } else { + area = find_vmap_area(addr); + } if (!area) usercopy_abort("vmalloc", "no area", to_user, 0, n); diff --git a/mm/vmalloc.c b/mm/vmalloc.c index dd6cdb201195..f14f1902c2f6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1840,6 +1840,17 @@ struct vmap_area *find_vmap_area(unsigned long addr) return va; } +struct vmap_area *find_vmap_area_try(unsigned long addr) +{ + struct vmap_area *va = NULL; + + if (spin_trylock(&vmap_area_lock)) { + va = __find_vmap_area(addr, &vmap_area_root); + spin_unlock(&vmap_area_lock); + } + return va; +} + /*** Per cpu kva allocator ***/ /* -- 2.34.1
