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authorFabio M. De Francesco <fmdefrancesco@gmail.com>2022-07-25 00:25:23 +0300
committerKees Cook <keescook@chromium.org>2022-07-28 00:15:09 +0300
commitc6e8e36c6ae4b11bed5643317afb66b6c3cadba8 (patch)
treed00ed947848a3c17a423d1f0f7734858479716a3 /fs
parent5036793d7dbd0b14aec51526441a50b01c7bf66d (diff)
downloadlinux-c6e8e36c6ae4b11bed5643317afb66b6c3cadba8.tar.xz
exec: Call kmap_local_page() in copy_string_kernel()
The use of kmap_atomic() is being deprecated in favor of kmap_local_page(). With kmap_local_page(), the mappings are per thread, CPU local and not globally visible. Furthermore, the mappings can be acquired from any context (including interrupts). Therefore, replace kmap_atomic() with kmap_local_page() in copy_string_kernel(). Instead of open-coding local mapping + memcpy(), use memcpy_to_page(). Delete a redundant call to flush_dcache_page(). Tested with xfstests on a QEMU/ KVM x86_32 VM, 6GB RAM, booting a kernel with HIGHMEM64GB enabled. Suggested-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220724212523.13317-1-fmdefrancesco@gmail.com
Diffstat (limited to 'fs')
-rw-r--r--fs/exec.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 0fc56c70c870..7e842d1bcb67 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -631,7 +631,6 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
unsigned int bytes_to_copy = min_t(unsigned int, len,
min_not_zero(offset_in_page(pos), PAGE_SIZE));
struct page *page;
- char *kaddr;
pos -= bytes_to_copy;
arg -= bytes_to_copy;
@@ -640,11 +639,8 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
page = get_arg_page(bprm, pos, 1);
if (!page)
return -E2BIG;
- kaddr = kmap_atomic(page);
flush_arg_page(bprm, pos & PAGE_MASK, page);
- memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy);
- flush_dcache_page(page);
- kunmap_atomic(kaddr);
+ memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
put_arg_page(page);
}