From: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
To: mcgrof@kernel.org, linux-modules@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, error27@gmail.com,
kernel-janitors@vger.kernel.org,
Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Subject: [PATCH] module: Fix use-after-free bug in read_file_mod_stats()
Date: Thu, 27 Apr 2023 22:59:33 -0700 [thread overview]
Message-ID: <20230428055933.2699308-1-harshit.m.mogalapalli@oracle.com> (raw)
Smatch warns:
kernel/module/stats.c:394 read_file_mod_stats()
warn: passing freed memory 'buf'
We are passing 'buf' to simple_read_from_buffer() after freeing it.
Fix this by changing the order of 'simple_read_from_buffer' and 'kfree'.
Fixes: df3e764d8e5c ("module: add debug stats to help identify memory pressure")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
---
Found with statis analysis, only compile tested.
---
kernel/module/stats.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/module/stats.c b/kernel/module/stats.c
index ad7b6ada29f2..6ab2c94d6bc3 100644
--- a/kernel/module/stats.c
+++ b/kernel/module/stats.c
@@ -276,6 +276,7 @@ static ssize_t read_file_mod_stats(struct file *file, char __user *user_buf,
struct mod_fail_load *mod_fail;
unsigned int len, size, count_failed = 0;
char *buf;
+ int ret;
u32 live_mod_count, fkreads, fdecompress, fbecoming, floads;
unsigned long total_size, text_size, ikread_bytes, ibecoming_bytes,
idecompress_bytes, imod_bytes, total_virtual_lost;
@@ -390,8 +391,9 @@ static ssize_t read_file_mod_stats(struct file *file, char __user *user_buf,
out_unlock:
mutex_unlock(&module_mutex);
out:
+ ret = simple_read_from_buffer(user_buf, count, ppos, buf, len);
kfree(buf);
- return simple_read_from_buffer(user_buf, count, ppos, buf, len);
+ return ret;
}
#undef MAX_PREAMBLE
#undef MAX_FAILED_MOD_PRINT
--
2.40.0
next reply other threads:[~2023-04-28 5:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-28 5:59 Harshit Mogalapalli [this message]
2023-05-17 6:33 ` [PATCH] module: Fix use-after-free bug in read_file_mod_stats() Harshit Mogalapalli
2023-05-22 21:21 ` Luis Chamberlain
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