diff options
| author | Fabio M. De Francesco <fmdefrancesco@gmail.com> | 2022-07-24 23:25:23 +0200 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2022-07-27 14:15:09 -0700 |
| commit | c6e8e36c6ae4b11bed5643317afb66b6c3cadba8 (patch) | |
| tree | d00ed947848a3c17a423d1f0f7734858479716a3 /fs/exec.c | |
| parent | 5036793d7dbd0b14aec51526441a50b01c7bf66d (diff) | |
| download | lwn-c6e8e36c6ae4b11bed5643317afb66b6c3cadba8.tar.gz lwn-c6e8e36c6ae4b11bed5643317afb66b6c3cadba8.zip | |
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/exec.c')
| -rw-r--r-- | fs/exec.c | 6 |
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); } |