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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-03-24 01:03:49 +0300 |
|---|---|---|
| committer | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-04-18 23:44:54 +0300 |
| commit | 1fa0949bede6de2b595da535c3ce69de8e130db2 (patch) | |
| tree | 67d310a16690caf710e5b70e40cc1d7051c77861 /include | |
| parent | e76018cb604ace486de9cf85898c14bb2b47faff (diff) | |
| download | linux-1fa0949bede6de2b595da535c3ce69de8e130db2.tar.xz | |
digsig.h: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:
struct foo {
int stuff;
struct boo array[];
};
By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.
Also, notice that, dynamic memory allocations won't be affected by
this change:
"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]
This issue was found with the help of Coccinelle.
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/digsig.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/digsig.h b/include/linux/digsig.h index 594fc66a395a..2ace69e41088 100644 --- a/include/linux/digsig.h +++ b/include/linux/digsig.h @@ -29,7 +29,7 @@ struct pubkey_hdr { uint32_t timestamp; /* key made, always 0 for now */ uint8_t algo; uint8_t nmpi; - char mpi[0]; + char mpi[]; } __packed; struct signature_hdr { @@ -39,7 +39,7 @@ struct signature_hdr { uint8_t hash; uint8_t keyid[8]; uint8_t nmpi; - char mpi[0]; + char mpi[]; } __packed; #if defined(CONFIG_SIGNATURE) || defined(CONFIG_SIGNATURE_MODULE) |