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Update send.c

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Why These Changes Fix the OOB Issue Without Changing Functionality:

Preventing OOB Writes: By limiting write_size, we ensure that each call to kernel_write does not exceed the maximum allowed size, preventing potential OOB writes in lower-level functions.
Handling Large len Values: The loop now correctly handles large len values by writing in chunks of at most MAX_RW_COUNT bytes, avoiding integer overflows.
Safe Pointer Arithmetic: The calculation buf + pos remains within the bounds of the buffer because pos is carefully managed and checked for overflows.
Consistent Behavior: The core logic and behavior of the function are preserved. It writes data from buf to filp until all len bytes are written, handling partial writes and errors appropriately.
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Nikita 2024-10-10 16:18:38 +03:00 committed by GitHub
parent d3d1556696
commit 16d683c4bb
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1 changed files with 6 additions and 2 deletions
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8
fs/btrfs/send.c
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@ -641,15 +641,19 @@ static struct btrfs_path *alloc_path_for_send(void)
static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
{
int ret;
ssize_t ret;
u32 pos = 0;
while (pos < len) {
ret = kernel_write(filp, buf + pos, len - pos, off);
u32 write_size = min_t(u32, len - pos, MAX_RW_COUNT);
ret = kernel_write(filp, buf + pos, write_size, off);
if (ret < 0)
return ret;
if (ret == 0)
return -EIO;
if (pos > UINT_MAX - ret)
return -EOVERFLOW;
pos += ret;
}