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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-01-16 16:03:27 -0600
committerJohan Hovold <johan@kernel.org>2020-01-17 11:44:23 +0100
commit50c3c5e1c1b000d6a321ffdc0003bc6b7ac0b0e5 (patch)
treeefea0e6b4557ac18e8e1d99c38727283998bd85f /drivers/usb
parente6421583953fd92eba1785f90b228d70345125d6 (diff)
downloadlinux-50c3c5e1c1b000d6a321ffdc0003bc6b7ac0b0e5.tar.bz2
USB: serial: garmin_gps: Use flexible-array member
Old code in the kernel uses 1-byte and 0-byte arrays to indicate the presence of a "variable length array": struct something { int length; u8 data[1]; }; struct something *instance; instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL); instance->length = size; memcpy(instance->data, source, size); There is also 0-byte arrays. Both cases pose confusion for things like sizeof(), CONFIG_FORTIFY_SOURCE, etc.[1] Instead, the preferred mechanism to declare variable-length types such as the one above is a flexible array member[2] which need to be the last member of a structure and empty-sized: struct something { int stuff; u8 data[]; }; Also, 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 unadvertenly introduced[3] to the codebase from now on. [1] https://github.com/KSPP/linux/issues/21 [2] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Signed-off-by: Johan Hovold <johan@kernel.org>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/serial/garmin_gps.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/serial/garmin_gps.c b/drivers/usb/serial/garmin_gps.c
index 633550ec3025..ffd984142171 100644
--- a/drivers/usb/serial/garmin_gps.c
+++ b/drivers/usb/serial/garmin_gps.c
@@ -104,7 +104,7 @@ struct garmin_packet {
int seq;
/* the real size of the data array, always > 0 */
int size;
- __u8 data[1];
+ __u8 data[];
};
/* structure used to keep the current state of the driver */