| Message ID | ZSVKwBmxQ1amv47E@work (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 446425648c5d19ff7564923863538e9fae93e916 |
| Headers | show |
| Series | [next] afs: Add __counted_by for struct afs_acl and use struct_size() | expand |
On Tue, Oct 10, 2023 at 06:59:44AM -0600, Gustavo A. R. Silva wrote: > Prepare for the coming implementation by GCC and Clang of the __counted_by > attribute. Flexible array members annotated with __counted_by can have > their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for > array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > functions). > > While there, use struct_size() helper, instead of the open-coded > version, to calculate the size for the allocation of the whole > flexible structure, including of course, the flexible-array member. > > This code was found with the help of Coccinelle, and audited and > fixed manually. > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > fs/afs/internal.h | 2 +- > fs/afs/xattr.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/afs/internal.h b/fs/afs/internal.h > index 469a717467a4..e263a58b82ba 100644 > --- a/fs/afs/internal.h > +++ b/fs/afs/internal.h > @@ -1116,7 +1116,7 @@ extern void afs_fs_inline_bulk_status(struct afs_operation *); > > struct afs_acl { > u32 size; > - u8 data[]; > + u8 data[] __counted_by(size); > }; It's surprising how many of these 2-member structs we have in the kernel that do the same basic thing. :) And I see that "size" is assigned before using "data", good. Reviewed-by: Kees Cook <keescook@chromium.org> -Kees
On Tue, Oct 10, 2023 at 03:53:28PM -0700, Kees Cook wrote: > It's surprising how many of these 2-member structs we have in the kernel > that do the same basic thing. :) 75. We have 75 of them: // Options: --all-includes @sized_byte_buffer@ identifier NAME, SIZE, ARRAY; typedef s8, s16, s32, s64; typedef __s8, __s16, __s32, __s64; typedef u8, u16, u32, u64; typedef __u8, __u16, __u32, __u64; type SIZE_TYPE = {char, short, int, long, long long, ssize_t, s8, s16, s32, s64, __s8, __s16, __s32, __s64, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, size_t, u8, u16, u32, u64, __u8, __u16, __u32, __u64}; type BYTE_TYPE = {char, unsigned char, u8, __u8}; @@ *struct NAME { SIZE_TYPE SIZE; BYTE_TYPE ARRAY[]; }; https://paste.ubuntu.com/p/39CyK9nyqX/ Agh
On Tue, 10 Oct 2023 06:59:44 -0600, Gustavo A. R. Silva wrote: > Prepare for the coming implementation by GCC and Clang of the __counted_by > attribute. Flexible array members annotated with __counted_by can have > their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for > array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family > functions). > > While there, use struct_size() helper, instead of the open-coded > version, to calculate the size for the allocation of the whole > flexible structure, including of course, the flexible-array member. > > [...] Applied to for-next/hardening, thanks! [1/1] afs: Add __counted_by for struct afs_acl and use struct_size() https://git.kernel.org/kees/c/7403e688f0c0 Take care,
diff --git a/fs/afs/internal.h b/fs/afs/internal.h index 469a717467a4..e263a58b82ba 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -1116,7 +1116,7 @@ extern void afs_fs_inline_bulk_status(struct afs_operation *); struct afs_acl { u32 size; - u8 data[]; + u8 data[] __counted_by(size); }; extern void afs_fs_fetch_acl(struct afs_operation *); diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c index 9048d8ccc715..8b42cac51660 100644 --- a/fs/afs/xattr.c +++ b/fs/afs/xattr.c @@ -75,7 +75,7 @@ static bool afs_make_acl(struct afs_operation *op, { struct afs_acl *acl; - acl = kmalloc(sizeof(*acl) + size, GFP_KERNEL); + acl = kmalloc(struct_size(acl, data, size), GFP_KERNEL); if (!acl) { afs_op_nomem(op); return false;
Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions). While there, use struct_size() helper, instead of the open-coded version, to calculate the size for the allocation of the whole flexible structure, including of course, the flexible-array member. This code was found with the help of Coccinelle, and audited and fixed manually. Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- fs/afs/internal.h | 2 +- fs/afs/xattr.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)