From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: akpm@linux-foundation.org
Cc: richard@nod.at, viro@zeniv.linux.org.uk,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH][Resend v2] Fix infinite loop in search_binary_handler()
Date: Thu, 07 Jul 2011 13:04:34 +0900 [thread overview]
Message-ID: <201107070404.p6744Ygd029169@www262.sakura.ne.jp> (raw)
In-Reply-To: <20110706132138.7e65a912.akpm@linux-foundation.org>
Andrew Morton wrote:
> What is that "for (try=0; try<2" loop actually there for? To retry
> after the request_module(), it appears. Which is pointless if
> !CONFIG_MODULES.
Indeed. This loop was introduced in Linux 1.3.57 (where CONFIG_KERNELD was
introduced). Comparing between 1.3.56 and 1.3.57, there is no reason to retry
if !CONFIG_KERNELD, for get_fs_type() in fs/super.c and dev_get() in
net/core/dev.c do not retry if !CONFIG_KERNELD.
struct file_system_type *get_fs_type(const char *name)
{
struct file_system_type * fs = file_systems;
if (!name)
return fs;
for (fs = file_systems; fs && strcmp(fs->name, name); fs = fs->next)
;
#ifdef CONFIG_KERNELD
if (!fs && (request_module(name) == 0)) {
for (fs = file_systems; fs && strcmp(fs->name, name); fs = fs->next)
;
}
#endif
return fs;
}
struct device *dev_get(const char *name)
{
struct device *dev;
for (dev = dev_base; dev != NULL; dev = dev->next)
{
if (strcmp(dev->name, name) == 0)
return(dev);
}
#ifdef CONFIG_KERNELD
if (request_module(name) == 0)
for (dev = dev_base; dev != NULL; dev = dev->next) {
if (strcmp(dev->name, name) == 0)
return(dev);
}
#endif
return(NULL);
}
It is likely that we have been doing needless retry if !CONFIG_MODULES.
----------------------------------------
[PATCH] exec: Do not retry load_binary method if CONFIG_MODULES=n.
If CONFIG_MODULES=n, it makes no sense to retry the list of binary formats
handler because the list will not be modified by request_module().
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
diff --git a/fs/exec.c b/fs/exec.c
index 6075a1e..46c399f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1401,9 +1401,9 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
}
}
read_unlock(&binfmt_lock);
+#ifdef CONFIG_MODULES
if (retval != -ENOEXEC || bprm->mm == NULL) {
break;
-#ifdef CONFIG_MODULES
} else {
#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
if (printable(bprm->buf[0]) &&
@@ -1412,8 +1412,10 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
printable(bprm->buf[3]))
break; /* -ENOEXEC */
request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
-#endif
}
+#else
+ break;
+#endif
}
return retval;
}
prev parent reply other threads:[~2011-07-07 4:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-04 11:30 [PATCH][Resend v2] Fix infinite loop in search_binary_handler() Richard Weinberger
2011-07-04 11:51 ` Tetsuo Handa
2011-07-04 11:57 ` Richard Weinberger
2011-07-04 12:10 ` Tetsuo Handa
2011-07-04 12:20 ` Richard Weinberger
2011-07-04 14:42 ` Tetsuo Handa
2011-07-04 14:59 ` Richard Weinberger
2011-07-04 15:07 ` Richard Weinberger
2011-07-04 22:03 ` Tetsuo Handa
2011-07-04 22:17 ` Richard Weinberger
2011-07-05 1:24 ` Tetsuo Handa
2011-07-05 9:55 ` Richard Weinberger
2011-07-05 12:02 ` Tetsuo Handa
2011-07-05 12:21 ` Richard Weinberger
2011-07-06 11:28 ` Tetsuo Handa
2011-07-06 11:36 ` Richard Weinberger
2011-07-06 20:21 ` Andrew Morton
2011-07-07 4:04 ` Tetsuo Handa [this message]
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