crypto: s5p-sss - Replace zero-length array with flexible-array member
PATCH 1/1 crypto: s5p-sss - 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")
--- drivers/crypto/s5p-sss.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/crypto/s5p-sss.c +1 -1
@@ -369,7 +369,7 @@ struct s5p_hash_reqctx {bool error;u32 bufcnt; -u8 buffer[0 ]; +u8 buffer[]; };/**
Signature · 1 line
2.25.0
Quoted 39 lines · Gustavo A. R. Silva
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://protect2.fireeye.com/url?k=7fbec6f4-22720d30-7fbf4dbb-0cc47a314e9a-2a4d03985644c7ed&u=https://github.com/KSPP/linux/issues/21
[3] commit76497732932f("cxgb3/l2t: Fix undefined behaviour")Signed-off-by Gustavo A. R. Silva <[email protected]>--- drivers/crypto/s5p-sss.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)drivers/crypto/s5p-sss.c +0
-0
drivers/crypto/s5p-sss.c struct s5p_hash_reqctx { · line 375
Quoted 8 lines
drivers/crypto/s5p-sss.c +1
-1@@ -369,7 +369,7 @@ struct s5p_hash_reqctx {bool error;u32 bufcnt; -u8 buffer[0 ]; +u8 buffer[]; };/**
Looks good to me.
Signature · 3 lines
Best regards, Kamil Konieczny Samsung R&D Institute Poland
Krzysztof Kozlowski
maintainerQuoted 47 lines · Kamil Konieczny
Quoted 45 lines · Gustavo A. R. Silva
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://protect2.fireeye.com/url?k=7fbec6f4-22720d30-7fbf4dbb-0cc47a314e9a-2a4d03985644c7ed&u=https://github.com/KSPP/linux/issues/21
[3] commit76497732932f("cxgb3/l2t: Fix undefined behaviour")Signed-off-by Gustavo A. R. Silva <[email protected]>--- drivers/crypto/s5p-sss.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)drivers/crypto/s5p-sss.c +1
-1@@ -369,7 +369,7 @@ struct s5p_hash_reqctx {bool error;u32 bufcnt; -u8 buffer[0 ]; +u8 buffer[]; };
Quoted 6 lines
drivers/crypto/s5p-sss.c struct s5p_hash_reqctx { · line 375
Quoted 2 lines
drivers/crypto/s5p-sss.c +0
-0/** Looks good to me.
Acked-by Kamil Konieczny <[email protected]>
Why not making it simple/obvious u8 *buffer? Or fixed length (BUFLEN length)?
Best regards,
Krzysztof
Herbert Xu
maintainerQuoted 24 lines · Gustavo A. R. Silva
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.
Quoted 8 lines
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit76497732932f("cxgb3/l2t: Fix undefined behaviour")Signed-off-by Gustavo A. R. Silva <[email protected]>--- drivers/crypto/s5p-sss.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Patch applied. Thanks.
Signature · 3 lines
Email: Herbert Xu <[email protected]> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt