On 3/30/21 23:53, Matthew Wilcox wrote: > On Tue, Mar 30, 2021 at 09:43:20PM -0700, Andrew Morton wrote: >> On Tue, 30 Mar 2021 09:52:26 -0500 "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx> wrote: >> >>> Fix the following out-of-bounds warnings by enclosing >>> structure members file and finder into new struct info: >>> >>> fs/hfsplus/xattr.c:300:5: warning: 'memcpy' offset [65, 80] from the object at 'entry' is out of the bounds of referenced subobject 'user_info' with type 'struct DInfo' at offset 48 [-Warray-bounds] >>> fs/hfsplus/xattr.c:313:5: warning: 'memcpy' offset [65, 80] from the object at 'entry' is out of the bounds of referenced subobject 'user_info' with type 'struct FInfo' at offset 48 [-Warray-bounds] >>> >>> Refactor the code by making it more "structured." >>> >>> Also, this helps with the ongoing efforts to enable -Warray-bounds and >>> makes the code clearer and avoid confusing the compiler. >> >> Confused. What was wrong with the old code? Was this warning >> legitimate and if so, why? Or is this patch a workaround for a >> compiler shortcoming? > > The offending line is this: > > - memcpy(&entry.file.user_info, value, > + memcpy(&entry.file.info, value, > file_finderinfo_len); > > what it's trying to do is copy two structs which are adjacent to each > other in a single call to memcpy(). gcc legitimately complains that the > memcpy to this struct overruns the bounds of the struct. What Gustavo > has done here is introduce a new struct that contains the two structs, > and now gcc is happy that the memcpy doesn't overrun the length of this > containing struct. Thanks for this, Matthew. :) -- Gustavo
