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From: Andrey Smirnov <andrew.smirnov@gmail.com>
To: barebox@lists.infradead.org
Cc: Andrey Smirnov <andrew.smirnov@gmail.com>
Subject: [PATCH v2 11/19] fs: Do not use IS_ERR_VALUE() to validate offset in lseek()
Date: Mon, 28 Jan 2019 22:55:41 -0800	[thread overview]
Message-ID: <20190129065549.29161-12-andrew.smirnov@gmail.com> (raw)
In-Reply-To: <20190129065549.29161-1-andrew.smirnov@gmail.com>

On 32-bit systems, checking for IS_ERR_VALUE(pos) is not
correct. Expanding that code we get (loff_t cast is added for clarity):

 (loff_t)pos >= (unsigned long)-MAX_ERRNO

given that loff_t is a 64-bit signed value, any perfectly valid seek
offset that is greater than 0xffffc000 will result in false positive.

Moreso, as a part of fix introduced in e10efc5080 ("fs: fix memory
access via /dev/mem for MIPS64") it doesn't really solve the problem
completely on on 64-bit platforms, becuase it still leaves out a
number of perfectly valid offsets (e.g. "md 0xffffffffffffff00"
doesn't work)

Undo the original change and convert the check to simply test if
offset is negative.

Changes neccessary to alllow access to end of 64-bit address space
will be implemented in the follow-up patch.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---
 fs/fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/fs.c b/fs/fs.c
index 7e62b89e4..2638e7458 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -420,7 +420,7 @@ loff_t lseek(int fildes, loff_t offset, int whence)
 	case SEEK_SET:
 		if (f->size != FILE_SIZE_STREAM && offset > f->size)
 			goto out;
-		if (IS_ERR_VALUE(offset))
+		if (offset < 0)
 			goto out;
 		pos = offset;
 		break;
-- 
2.20.1


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  parent reply	other threads:[~2019-01-29  6:56 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-29  6:55 [PATCH v2 00/19] 32-bit lseek and /dev/mem fixes/improvements Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 01/19] commands: Move mem_parse_options() to lib/misc.c Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 02/19] commands: Get rid of mem_rw_buf Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 03/19] commands: Move /dev/mem driver to drivers/misc Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 04/19] nvmem: Do not use DEVFS_IS_CHARACTER_DEV Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 05/19] common: firmware: Don't use FILE_SIZE_STREAM directly Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 06/19] devfs: Fix incorrect error check for cdev->ops->lseek() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 07/19] fs: Update FILE position in lseek() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 08/19] fs: Drop trivial .lseek() implementaitons in FS drivers Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 09/19] devfs: Drop dev_lseek_default() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 10/19] fs: devfs: Change .lseek callbacks to return 'int' Andrey Smirnov
2019-02-04 14:32   ` Sascha Hauer
2019-01-29  6:55 ` Andrey Smirnov [this message]
2019-01-29  6:55 ` [PATCH v2 12/19] fs: Simplify new position calculation in lseek() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 13/19] fs: Share code between mem_write()/mem_read() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 14/19] fs: Avoid division in mem_copy() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 15/19] fs: Report actual data processed by mem_copy() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 16/19] fs: Introduce mem_read_nofail() Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 17/19] commands: md: Do not use memmap() Andrey Smirnov
2019-02-04 13:57   ` Sascha Hauer
2019-02-04 19:35     ` Andrey Smirnov
2019-01-29  6:55 ` [PATCH v2 18/19] drivers: mem: Create file to access second half of 64-bit memory Andrey Smirnov
2019-01-29  8:48   ` Sascha Hauer
2019-01-29 20:40     ` Andrey Smirnov
2019-01-29 21:09       ` Sam Ravnborg
2019-01-31 10:54       ` Peter Mamonov
2019-01-31 12:50         ` Peter Mamonov
2019-02-01  7:47           ` Sascha Hauer
2019-02-01 10:25             ` Peter Mamonov
2019-02-02  1:07               ` Andrey Smirnov
2019-02-02  0:35             ` Andrey Smirnov
2019-02-04  7:40               ` Sascha Hauer
2019-01-31 20:17         ` Andrey Smirnov
2019-02-01 10:14           ` Peter Mamonov
2019-01-29  6:55 ` [PATCH v2 19/19] libfile: Fix incorrect lseek check in open_and_lseek() Andrey Smirnov

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