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Date: Thu, 25 Jul 2019 10:38:31 -0400
From: Qian Cai <cai@....pw>
To: akpm@...ux-foundation.org
Cc: tobin@...nel.org, rostedt@...dmis.org, mingo@...hat.com,
tj@...nel.org, dchinner@...hat.com, fengguang.wu@...el.com,
jack@...e.cz, axboe@...nel.dk, linux-kernel@...r.kernel.org,
Qian Cai <cai@....pw>
Subject: [PATCH v2] writeback: fix -Wstringop-truncation warnings
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@....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);
__entry->ino = mapping ? mapping->host->i_ino : 0;
__entry->index = page->index;
),
@@ -110,8 +112,8 @@
struct backing_dev_info *bdi = inode_to_bdi(inode);
/* may be called for files on pseudo FSes w/ unregistered bdi */
- strncpy(__entry->name,
- bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+ strscpy_pad(__entry->name,
+ bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->flags = flags;
@@ -190,8 +192,8 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
),
TP_fast_assign(
- strncpy(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ strscpy_pad(__entry->name,
+ dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->sync_mode = wbc->sync_mode;
__entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc);
@@ -234,8 +236,9 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name,
- wb->bdi->dev ? dev_name(wb->bdi->dev) : "(unknown)", 32);
+ strscpy_pad(__entry->name,
+ wb->bdi->dev ? dev_name(wb->bdi->dev) :
+ "(unknown)", 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
__entry->sync_mode = work->sync_mode;
@@ -288,7 +291,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
__field(unsigned int, cgroup_ino)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32);
__entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
),
TP_printk("bdi %s: cgroup_ino=%u",
@@ -310,7 +313,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
__array(char, name, 32)
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strscpy_pad(__entry->name, dev_name(bdi->dev), 32);
),
TP_printk("bdi %s",
__entry->name
@@ -335,7 +338,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(bdi->dev), 32);
+ strscpy_pad(__entry->name, dev_name(bdi->dev), 32);
__entry->nr_to_write = wbc->nr_to_write;
__entry->pages_skipped = wbc->pages_skipped;
__entry->sync_mode = wbc->sync_mode;
@@ -386,7 +389,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
),
TP_fast_assign(
unsigned long *older_than_this = work->older_than_this;
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32);
__entry->older = older_than_this ? *older_than_this : 0;
__entry->age = older_than_this ?
(jiffies - *older_than_this) * 1000 / HZ : -1;
@@ -472,7 +475,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
),
TP_fast_assign(
- strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32);
__entry->write_bw = KBps(wb->write_bandwidth);
__entry->avg_write_bw = KBps(wb->avg_write_bandwidth);
__entry->dirty_rate = KBps(dirty_rate);
@@ -537,7 +540,7 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
TP_fast_assign(
unsigned long freerun = (thresh + bg_thresh) / 2;
- strlcpy(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32);
__entry->limit = global_wb_domain.dirty_limit;
__entry->setpoint = (global_wb_domain.dirty_limit +
@@ -597,8 +600,8 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
),
TP_fast_assign(
- strncpy(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ strscpy_pad(__entry->name,
+ dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
@@ -671,8 +674,8 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
),
TP_fast_assign(
- strncpy(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ strscpy_pad(__entry->name,
+ dev_name(inode_to_bdi(inode)->dev), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
--
1.8.3.1
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