Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH v2] writeback: fix -Wstringop-truncation warnings | Date | Thu, 25 Jul 2019 15:04:02 +0000 |
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From: Qian Cai > Sent: 25 July 2019 15:39 > > There are many of those warnings. > > In file included from ./arch/powerpc/include/asm/paca.h:15, > from ./arch/powerpc/include/asm/current.h:13, > from ./include/linux/thread_info.h:21, > from ./include/asm-generic/preempt.h:5, > from ./arch/powerpc/include/generated/asm/preempt.h:1, > from ./include/linux/preempt.h:78, > from ./include/linux/spinlock.h:51, > from fs/fs-writeback.c:19: > In function 'strncpy', > inlined from 'perf_trace_writeback_page_template' at > ./include/trace/events/writeback.h:56:1: > ./include/linux/string.h:260:9: warning: '__builtin_strncpy' specified > bound 32 equals destination size [-Wstringop-truncation] > return __builtin_strncpy(p, q, size); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Fix it by using the new strscpy_pad() which was introduced in the > commit 458a3bf82df4 ("lib/string: Add strscpy_pad() function") and will > always be NUL-terminated instead of strncpy(). Also, changes strlcpy() > to use strscpy_pad() in this file for consistency. > > Fixes: 455b2864686d ("writeback: Initial tracing support") > Fixes: 028c2dd184c0 ("writeback: Add tracing to balance_dirty_pages") > Fixes: e84d0a4f8e39 ("writeback: trace event writeback_queue_io") > Fixes: b48c104d2211 ("writeback: trace event bdi_dirty_ratelimit") > Fixes: cc1676d917f3 ("writeback: Move requeueing when I_SYNC set to writeback_sb_inodes()") > Fixes: 9fb0a7da0c52 ("writeback: add more tracepoints") > Signed-off-by: Qian Cai <cai@lca.pw> > --- > > v2: Use strscpy_pad() to address the possible data leaking concern from Steve [1]. > Replace strlcpy() as well for consistency. > > [1] https://lore.kernel.org/lkml/20190716170339.1c44719d@gandalf.local.home/ > > include/trace/events/writeback.h | 39 +++++++++++++++++++++------------------ > 1 file changed, 21 insertions(+), 18 deletions(-) > > diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h > index aa7f3aeac740..41092d63a8de 100644 > --- a/include/trace/events/writeback.h > +++ b/include/trace/events/writeback.h > @@ -66,8 +66,10 @@ > ), > > TP_fast_assign( > - strncpy(__entry->name, > - mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32); > + strscpy_pad(__entry->name, > + mapping ? > + dev_name(inode_to_bdi(mapping->host)->dev) : > + "(unknown)", 32);
Shouldn't the 32 be 'sizeof (something)' ??
Oh, and a horrid line break.
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
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