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authorPeter Hurley <peter@hurleysoftware.com>2013-11-22 07:16:25 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-11-25 08:36:56 -0800
commitc77569d2f3ef7844ee4ac7005a57da6898b302a8 (patch)
tree9c7b1fffb698f410a86463fcc700bec3fca8f6fc /drivers/tty/n_tty.c
parent6f2225363c205e186c1465c2c7c84f17c1635504 (diff)
downloadop-kernel-dev-c77569d2f3ef7844ee4ac7005a57da6898b302a8.zip
op-kernel-dev-c77569d2f3ef7844ee4ac7005a57da6898b302a8.tar.gz
n_tty: Fix 4096-byte canonical reads
Although the maximum allowable canonical line is specified to be 255 bytes (MAX_CANON), the practical limit has actually been the size of the line discipline read buffer (N_TTY_BUF_SIZE == 4096). Commit 32f13521ca68bc624ff6effc77f308a52b038bf0, n_tty: Line copy to user buffer in canonical mode, limited the line copy to 4095 bytes. With a completely full line discipline read buffer and a userspace buffer > 4095, _no_ data was copied, and the read() syscall returned 0, indicating EOF. Fix the interval arithmetic to compute the correct number of bytes to copy to userspace in the range [1..4096]. Cc: <stable@vger.kernel.org> # 3.12.x Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_tty.c')
-rw-r--r--drivers/tty/n_tty.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index d8a779d..c222a56 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1998,7 +1998,10 @@ static int canon_copy_from_read_buf(struct tty_struct *tty,
found = 1;
size = N_TTY_BUF_SIZE - tail;
- n = (found + eol + size) & (N_TTY_BUF_SIZE - 1);
+ n = eol - tail;
+ if (n > 4096)
+ n += 4096;
+ n += found;
c = n;
if (found && read_buf(ldata, eol) == __DISABLED_CHAR) {
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