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nilfs2: fix possible int overflows in nilfs_fiemap()

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Since nilfs_bmap_lookup_contig() in nilfs_fiemap() calculates its result
by being prepared to go through potentially maxblocks == INT_MAX blocks,
the value in n may experience an overflow caused by left shift of blkbits.

While it is extremely unlikely to occur, play it safe and cast right hand
expression to wider type to mitigate the issue.

Found by Linux Verification Center (linuxtesting.org) with static analysis
tool SVACE.

Link: https://lkml.kernel.org/r/20250124222133.5323-1-konishi.ryusuke@gmail.com
Fixes: 622daaff0a ("nilfs2: fiemap support")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Nikita Zhandarovich 2025-01-25 07:20:53 +09:00 • committed by Andrew Morton
parent 6268f0a166
commit 6438ef381c
1 changed files with 3 additions and 3 deletions
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6
fs/nilfs2/inode.c
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@ -1186,7 +1186,7 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
if (size) {
if (phys && blkphy << blkbits == phys + size) {
/* The current extent goes on */
size += n << blkbits;
size += (u64)n << blkbits;
} else {
/* Terminate the current extent */
ret = fiemap_fill_next_extent(
@ -1199,14 +1199,14 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
flags = FIEMAP_EXTENT_MERGED;
logical = blkoff << blkbits;
phys = blkphy << blkbits;
size = n << blkbits;
size = (u64)n << blkbits;
}
} else {
/* Start a new extent */
flags = FIEMAP_EXTENT_MERGED;
logical = blkoff << blkbits;
phys = blkphy << blkbits;
size = n << blkbits;
size = (u64)n << blkbits;
}
blkoff += n;
}