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s390/zcore: fix race when reading from hardware system area

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Memory buffer used for reading out data from hardware system
area is not protected against concurrent access.

Reported-by: Matthew Wilcox <willy@infradead.org>
Fixes: 411ed32257 ("[S390] zfcpdump support.")
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Link: https://lore.kernel.org/r/e68137f0f9a0d2558f37becc20af18e2939934f6.1658206891.git.agordeev@linux.ibm.com
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Alexander Gordeev 2022-07-19 07:16:33 +02:00
parent f6749da17a
commit 9ffed254d9
1 changed files with 10 additions and 1 deletions
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11
drivers/s390/char/zcore.c
View File

@ -50,6 +50,7 @@ static struct dentry *zcore_reipl_file;
static struct dentry *zcore_hsa_file;
static struct ipl_parameter_block *zcore_ipl_block;
static DEFINE_MUTEX(hsa_buf_mutex);
static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
/*
@ -66,19 +67,24 @@ int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
if (!hsa_available)
return -ENODATA;
mutex_lock(&hsa_buf_mutex);
while (count) {
if (sclp_sdias_copy(hsa_buf, src / PAGE_SIZE + 2, 1)) {
TRACE("sclp_sdias_copy() failed\n");
mutex_unlock(&hsa_buf_mutex);
return -EIO;
}
offset = src % PAGE_SIZE;
bytes = min(PAGE_SIZE - offset, count);
if (copy_to_user(dest, hsa_buf + offset, bytes))
if (copy_to_user(dest, hsa_buf + offset, bytes)) {
mutex_unlock(&hsa_buf_mutex);
return -EFAULT;
}
src += bytes;
dest += bytes;
count -= bytes;
}
mutex_unlock(&hsa_buf_mutex);
return 0;
}
@ -96,9 +102,11 @@ int memcpy_hsa_kernel(void *dest, unsigned long src, size_t count)
if (!hsa_available)
return -ENODATA;
mutex_lock(&hsa_buf_mutex);
while (count) {
if (sclp_sdias_copy(hsa_buf, src / PAGE_SIZE + 2, 1)) {
TRACE("sclp_sdias_copy() failed\n");
mutex_unlock(&hsa_buf_mutex);
return -EIO;
}
offset = src % PAGE_SIZE;
@ -108,6 +116,7 @@ int memcpy_hsa_kernel(void *dest, unsigned long src, size_t count)
dest += bytes;
count -= bytes;
}
mutex_unlock(&hsa_buf_mutex);
return 0;
}