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authorlianzhi chang <changlianzhi@uniontech.com>2021-01-14 15:57:41 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-02-07 15:37:15 +0100
commita9fd4ef6e50c22a303afaa9ebfd7e0fea0d5d1ff (patch)
treeeccf610fa5aca5069517fa8e846eeea1b4ce0be6 /fs/udf
parent40545c4dd90c96f8f4ecd7eac7b107e14f467619 (diff)
udf: fix the problem that the disc content is not displayed
[ Upstream commit 5cdc4a6950a883594e9640b1decb3fcf6222a594 ] When the capacity of the disc is too large (assuming the 4.7G specification), the disc (UDF file system) will be burned multiple times in the windows (Multisession Usage). When the remaining capacity of the CD is less than 300M (estimated value, for reference only), open the CD in the Linux system, the content of the CD is displayed as blank (the kernel will say "No VRS found"). Windows can display the contents of the CD normally. Through analysis, in the "fs/udf/super.c": udf_check_vsd function, the actual value of VSD_MAX_SECTOR_OFFSET may be much larger than 0x800000. According to the current code logic, it is found that the type of sbi->s_session is "__s32", when the remaining capacity of the disc is less than 300M (take a set of test values: sector=3154903040, sbi->s_session=1540464, sb->s_blocksize_bits=11 ), the calculation result of "sbi->s_session << sb->s_blocksize_bits" will overflow. Therefore, it is necessary to convert the type of s_session to "loff_t" (when udf_check_vsd starts, assign a value to _sector, which is also converted in this way), so that the result will not overflow, and then the content of the disc can be displayed normally. Link: https://lore.kernel.org/r/20210114075741.30448-1-changlianzhi@uniontech.com Signed-off-by: lianzhi chang <changlianzhi@uniontech.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs/udf')
-rw-r--r--fs/udf/super.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/udf/super.c b/fs/udf/super.c
index 5bef3a68395d..d0df217f4712 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -705,6 +705,7 @@ static int udf_check_vsd(struct super_block *sb)
struct buffer_head *bh = NULL;
int nsr = 0;
struct udf_sb_info *sbi;
+ loff_t session_offset;
sbi = UDF_SB(sb);
if (sb->s_blocksize < sizeof(struct volStructDesc))
@@ -712,7 +713,8 @@ static int udf_check_vsd(struct super_block *sb)
else
sectorsize = sb->s_blocksize;
- sector += (((loff_t)sbi->s_session) << sb->s_blocksize_bits);
+ session_offset = (loff_t)sbi->s_session << sb->s_blocksize_bits;
+ sector += session_offset;
udf_debug("Starting at sector %u (%lu byte sectors)\n",
(unsigned int)(sector >> sb->s_blocksize_bits),
@@ -757,8 +759,7 @@ static int udf_check_vsd(struct super_block *sb)
if (nsr > 0)
return 1;
- else if (!bh && sector - (sbi->s_session << sb->s_blocksize_bits) ==
- VSD_FIRST_SECTOR_OFFSET)
+ else if (!bh && sector - session_offset == VSD_FIRST_SECTOR_OFFSET)
return -1;
else
return 0;