Messages in this thread Patch in this message | | | From | Mathieu Malaterre <> | Subject | [PATCH] writeback: tracing: Copy only up to 31 characters in strncpy() calls | Date | Fri, 18 Jan 2019 20:32:00 +0100 |
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In the past an attempt was made to remove a set of warnings triggered by gcc 8.x and W=1 by changing calls to strncpy() into strlcpy(). This was rejected as one of the desired behavior is to keep initializing the rest of the destination string whenever the source string is less than the size.
However the code makes it clear that this is not a desired behavior to copy the entire 32 characters into the destination buffer, since it is expected that the string is NUL terminated. So change the maximum number of characters to be copied to be the size of the destination buffer minus 1.
Break long lines and make this patch go through `checkpatch --strict` with no errors.
This commit removes the following warnings:
include/trace/events/writeback.h:69:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:99:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:179:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:223:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:277:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:299:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:324:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:375:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:586:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation] include/trace/events/writeback.h:660:3: warning: 'strncpy' specified bound 32 equals destination size [-Wstringop-truncation]
Cc: Nick Desaulniers <nick.desaulniers@gmail.com> Link: https://lore.kernel.org/patchwork/patch/910830/ Signed-off-by: Mathieu Malaterre <malat@debian.org> --- include/trace/events/writeback.h | 30 ++++++++++++++++++++---------- 1 file changed, 20 insertions(+), 10 deletions(-)
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 32db72c7c055..7bc58980f84f 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -67,7 +67,8 @@ TRACE_EVENT(writeback_dirty_page, TP_fast_assign( strncpy(__entry->name, - mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)", 32); + mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : + "(unknown)", sizeof(__entry->name) - 1); __entry->ino = mapping ? mapping->host->i_ino : 0; __entry->index = page->index; ), @@ -97,7 +98,8 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template, /* may be called for files on pseudo FSes w/ unregistered bdi */ strncpy(__entry->name, - bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32); + bdi->dev ? dev_name(bdi->dev) : "(unknown)", + sizeof(__entry->name) - 1); __entry->ino = inode->i_ino; __entry->state = inode->i_state; __entry->flags = flags; @@ -177,7 +179,8 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template, TP_fast_assign( strncpy(__entry->name, - dev_name(inode_to_bdi(inode)->dev), 32); + dev_name(inode_to_bdi(inode)->dev), + sizeof(__entry->name) - 1); __entry->ino = inode->i_ino; __entry->sync_mode = wbc->sync_mode; __entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc); @@ -221,7 +224,8 @@ DECLARE_EVENT_CLASS(writeback_work_class, ), TP_fast_assign( strncpy(__entry->name, - wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32); + wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", + sizeof(__entry->name) - 1); __entry->nr_pages = work->nr_pages; __entry->sb_dev = work->sb ? work->sb->s_dev : 0; __entry->sync_mode = work->sync_mode; @@ -274,7 +278,8 @@ DECLARE_EVENT_CLASS(writeback_class, __field(unsigned int, cgroup_ino) ), TP_fast_assign( - strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + strncpy(__entry->name, dev_name(wb->bdi->dev), + sizeof(__entry->name) - 1); __entry->cgroup_ino = __trace_wb_assign_cgroup(wb); ), TP_printk("bdi %s: cgroup_ino=%u", @@ -296,7 +301,8 @@ TRACE_EVENT(writeback_bdi_register, __array(char, name, 32) ), TP_fast_assign( - strncpy(__entry->name, dev_name(bdi->dev), 32); + strncpy(__entry->name, dev_name(bdi->dev), + sizeof(__entry->name) - 1); ), TP_printk("bdi %s", __entry->name @@ -321,7 +327,8 @@ DECLARE_EVENT_CLASS(wbc_class, ), TP_fast_assign( - strncpy(__entry->name, dev_name(bdi->dev), 32); + strncpy(__entry->name, dev_name(bdi->dev), + sizeof(__entry->name) - 1); __entry->nr_to_write = wbc->nr_to_write; __entry->pages_skipped = wbc->pages_skipped; __entry->sync_mode = wbc->sync_mode; @@ -372,7 +379,8 @@ TRACE_EVENT(writeback_queue_io, ), TP_fast_assign( unsigned long *older_than_this = work->older_than_this; - strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + strncpy(__entry->name, dev_name(wb->bdi->dev), + sizeof(__entry->name) - 1); __entry->older = older_than_this ? *older_than_this : 0; __entry->age = older_than_this ? (jiffies - *older_than_this) * 1000 / HZ : -1; @@ -584,7 +592,8 @@ TRACE_EVENT(writeback_sb_inodes_requeue, TP_fast_assign( strncpy(__entry->name, - dev_name(inode_to_bdi(inode)->dev), 32); + dev_name(inode_to_bdi(inode)->dev), + sizeof(__entry->name) - 1); __entry->ino = inode->i_ino; __entry->state = inode->i_state; __entry->dirtied_when = inode->dirtied_when; @@ -658,7 +667,8 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template, TP_fast_assign( strncpy(__entry->name, - dev_name(inode_to_bdi(inode)->dev), 32); + dev_name(inode_to_bdi(inode)->dev), + sizeof(__entry->name) - 1); __entry->ino = inode->i_ino; __entry->state = inode->i_state; __entry->dirtied_when = inode->dirtied_when; -- 2.19.2
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