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ext4 crypto: allocate the right amount of memory for the on-disk symlink

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Previously we were taking the required padding when allocating space
for the on-disk symlink.  This caused a buffer overrun which could
trigger a krenel crash when running fsstress.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
2015-05-31 13:35:32 -04:00
parent 82d0d3e7e6
commit 4d3c4e5b8c
3 changed files with 37 additions and 21 deletions
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25
fs/ext4/crypto_fname.c
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@@ -262,8 +262,20 @@ u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
return ((size+blksize-1)/blksize)*blksize;
}
/**
* ext4_fname_crypto_alloc_obuff() -
unsigned ext4_fname_encrypted_size(struct inode *inode, u32 ilen)
{
struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
int padding = 32;
if (ci)
padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
if (ilen < EXT4_CRYPTO_BLOCK_SIZE)
ilen = EXT4_CRYPTO_BLOCK_SIZE;
return ext4_fname_crypto_round_up(ilen, padding);
}
/*
* ext4_fname_crypto_alloc_buffer() -
*
* Allocates an output buffer that is sufficient for the crypto operation
* specified by the context and the direction.
@@ -271,15 +283,8 @@ u32 ext4_fname_crypto_round_up(u32 size, u32 blksize)
int ext4_fname_crypto_alloc_buffer(struct inode *inode,
u32 ilen, struct ext4_str *crypto_str)
{
unsigned int olen;
int padding = 16;
struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
unsigned int olen = ext4_fname_encrypted_size(inode, ilen);
if (ci)
padding = 4 << (ci->ci_flags & EXT4_POLICY_FLAGS_PAD_MASK);
if (padding < EXT4_CRYPTO_BLOCK_SIZE)
padding = EXT4_CRYPTO_BLOCK_SIZE;
olen = ext4_fname_crypto_round_up(ilen, padding);
crypto_str->len = olen;
if (olen < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2)
olen = EXT4_FNAME_CRYPTO_DIGEST_SIZE*2;