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| author | Xi Wang <xi.wang@gmail.com> | 2012-04-25 20:45:22 +0200 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2012-05-14 06:05:15 +0200 |
| commit | 7c80c352331a27cf0584f1701ed3a003984985f0 (patch) | |
| tree | 3c90b8d5a23cf563fb40a9866bc8dcf11af4b2fc | |
| parent | mtd: cmdlinepart: fix commentary (diff) | |
| download | linux-7c80c352331a27cf0584f1701ed3a003984985f0.tar.xz linux-7c80c352331a27cf0584f1701ed3a003984985f0.zip | |
jffs2: validate symlink size in jffs2_do_read_inode_internal()
`csize' is read from disk and thus needs validation. Otherwise a bogus
value 0xffffffff would turn the subsequent kmalloc(csize + 1, ...) into
kmalloc(0, ...), leading to out-of-bounds write.
This patch limits `csize' to JFFS2_MAX_NAME_LEN, which is also used
in jffs2_symlink().
Artem: we actually validate csize by checking CRC, so this 0xFFs cannot
come from empty flash region. But I guess an attacker could feed JFFS2
an image with random csize value, including 0xFFs.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
| -rw-r--r-- | fs/jffs2/readinode.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c index dc0437e84763..9897f38af707 100644 --- a/fs/jffs2/readinode.c +++ b/fs/jffs2/readinode.c @@ -1266,6 +1266,12 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c, /* Symlink's inode data is the target path. Read it and * keep in RAM to facilitate quick follow symlink * operation. */ + uint32_t csize = je32_to_cpu(latest_node->csize); + if (csize > JFFS2_MAX_NAME_LEN) { + mutex_unlock(&f->sem); + jffs2_do_clear_inode(c, f); + return -ENAMETOOLONG; + } f->target = kmalloc(je32_to_cpu(latest_node->csize) + 1, GFP_KERNEL); if (!f->target) { JFFS2_ERROR("can't allocate %d bytes of memory for the symlink target path cache\n", je32_to_cpu(latest_node->csize)); |