Linux-stable-mirror

linux-stable-mirror@lists.linaro.org

265 participants
124086 discussions

[PATCH] Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again"

by Paul Burton

Commit f6aa5beb45be ("serial: 8250: Fix clearing FIFOs in RS485 mode again") makes a change to FIFO clearing code which its commit message suggests was intended to be specific to use with RS485 mode, however: 1) The change made does not just affect __do_stop_tx_rs485(), it also affects other uses of serial8250_clear_fifos() including paths for starting up, shutting down or auto-configuring a port regardless of whether it's an RS485 port or not. 2) It makes the assumption that resetting the FIFOs is a no-op when FIFOs are disabled, and as such it checks for this case & explicitly avoids setting the FIFO reset bits when the FIFO enable bit is clear. A reading of the PC16550D manual would suggest that this is OK since the FIFO should automatically be reset if it is later enabled, but we support many 16550-compatible devices and have never required this auto-reset behaviour for at least the whole git era. Starting to rely on it now seems risky, offers no benefit, and indeed breaks at least the Ingenic JZ4780's UARTs which reads garbage when the RX FIFO is enabled if we don't explicitly reset it. 3) By only resetting the FIFOs if they're enabled, the behaviour of serial8250_do_startup() during boot now depends on what the value of FCR is before the 8250 driver is probed. This in itself seems questionable and leaves us with FCR=0 & no FIFO reset if the UART was used by 8250_early, otherwise it depends upon what the bootloader left behind. 4) Although the naming of serial8250_clear_fifos() may be unclear, it is clear that callers of it expect that it will disable FIFOs. Both serial8250_do_startup() & serial8250_do_shutdown() contain comments to that effect, and other callers explicitly re-enable the FIFOs after calling serial8250_clear_fifos(). The premise of that patch that disabling the FIFOs is incorrect therefore seems wrong. For these reasons, this reverts commit f6aa5beb45be ("serial: 8250: Fix clearing FIFOs in RS485 mode again"). Signed-off-by: Paul Burton <paul.burton(a)mips.com> Fixes: f6aa5beb45be ("serial: 8250: Fix clearing FIFOs in RS485 mode again"). Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: Daniel Jedrychowski <avistel(a)gmail.com> Cc: Marek Vasut <marex(a)denx.de> Cc: linux-mips(a)vger.kernel.org Cc: linux-serial(a)vger.kernel.org Cc: stable <stable(a)vger.kernel.org> # 4.10+ --- I did suggest an alternative approach which would rename serial8250_clear_fifos() and split it into 2 variants - one that disables FIFOs & one that does not, then use the latter in __do_stop_tx_rs485(): https://lore.kernel.org/lkml/20181213014805.77u5dzydo23cm6fq@pburton-laptop/ However I have no access to the OMAP3 hardware that Marek's patch was attempting to fix & have heard nothing back with regards to him testing that approach, so here's a simple revert that fixes the Ingenic JZ4780. I've marked for stable back to v4.10 presuming that this is how far the broken patch may be backported, given that this is where commit 2bed8a8e7072 ("Clearing FIFOs in RS485 emulation mode causes subsequent transmits to break") that it tried to fix was introduced. --- drivers/tty/serial/8250/8250_port.c | 29 +++++------------------------ 1 file changed, 5 insertions(+), 24 deletions(-) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index f776b3eafb96..3f779d25ec0c 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -552,30 +552,11 @@ static unsigned int serial_icr_read(struct uart_8250_port *up, int offset) */ static void serial8250_clear_fifos(struct uart_8250_port *p) { - unsigned char fcr; - unsigned char clr_mask = UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT; - if (p->capabilities & UART_CAP_FIFO) { - /* - * Make sure to avoid changing FCR[7:3] and ENABLE_FIFO bits. - * In case ENABLE_FIFO is not set, there is nothing to flush - * so just return. Furthermore, on certain implementations of - * the 8250 core, the FCR[7:3] bits may only be changed under - * specific conditions and changing them if those conditions - * are not met can have nasty side effects. One such core is - * the 8250-omap present in TI AM335x. - */ - fcr = serial_in(p, UART_FCR); - - /* FIFO is not enabled, there's nothing to clear. */ - if (!(fcr & UART_FCR_ENABLE_FIFO)) - return; - - fcr |= clr_mask; - serial_out(p, UART_FCR, fcr); - - fcr &= ~clr_mask; - serial_out(p, UART_FCR, fcr); + serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO); + serial_out(p, UART_FCR, UART_FCR_ENABLE_FIFO | + UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT); + serial_out(p, UART_FCR, 0); } } @@ -1467,7 +1448,7 @@ static void __do_stop_tx_rs485(struct uart_8250_port *p) * Enable previously disabled RX interrupts. */ if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) { - serial8250_clear_fifos(p); + serial8250_clear_and_reinit_fifos(p); p->ier |= UART_IER_RLSI | UART_IER_RDI; serial_port_out(&p->port, UART_IER, p->ier); -- 2.20.0

7 years

[PATCH v2] fs: fix possible Spectre V1 indexing in __close_fd()

by Greg Hackmann

Omer Tripp's analysis of a Spectre V1 gadget in __close_fd(): "1. __close_fd() is reachable via the close() syscall with a user-controlled fd. 2. If said bounds check is mispredicted, then a user-controlled address fdt->fd[fd] is obtained then dereferenced, and the value of a user-controlled address is loaded into the local variable file. 3. file is then passed as an argument to filp_close, where the cache lines secret + offsetof(f_op) and secret + offsetof(f_mode) are hot and vulnerable to a timing channel attack." Address this by using array_index_nospec() to prevent speculation past the end of current->fdt. Reported-by: Omer Tripp <trippo(a)google.com> Cc: stable(a)vger.kernel.org Signed-off-by: Greg Hackmann <ghackmann(a)android.com> --- v2: include Omer Tripp's analysis in commit message, and update my email address fs/file.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/file.c b/fs/file.c index 7ffd6e9d103d..a80cf82be96b 100644 --- a/fs/file.c +++ b/fs/file.c @@ -18,6 +18,7 @@ #include <linux/bitops.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <linux/nospec.h> unsigned int sysctl_nr_open __read_mostly = 1024*1024; unsigned int sysctl_nr_open_min = BITS_PER_LONG; @@ -626,6 +627,7 @@ int __close_fd(struct files_struct *files, unsigned fd) fdt = files_fdtable(files); if (fd >= fdt->max_fds) goto out_unlock; + fd = array_index_nospec(fd, fdt->max_fds); file = fdt->fd[fd]; if (!file) goto out_unlock; -- 2.19.1

7 years

FAILED: patch "[PATCH] futex: Cure exit race" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From da791a667536bf8322042e38ca85d55a78d3c273 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx(a)linutronix.de> Date: Mon, 10 Dec 2018 14:35:14 +0100 Subject: [PATCH] futex: Cure exit race Stefan reported, that the glibc tst-robustpi4 test case fails occasionally. That case creates the following race between sys_exit() and sys_futex_lock_pi(): CPU0 CPU1 sys_exit() sys_futex() do_exit() futex_lock_pi() exit_signals(tsk) No waiters: tsk->flags |= PF_EXITING; *uaddr == 0x00000PID mm_release(tsk) Set waiter bit exit_robust_list(tsk) { *uaddr = 0x80000PID; Set owner died attach_to_pi_owner() { *uaddr = 0xC0000000; tsk = get_task(PID); } if (!tsk->flags & PF_EXITING) { ... attach(); tsk->flags |= PF_EXITPIDONE; } else { if (!(tsk->flags & PF_EXITPIDONE)) return -EAGAIN; return -ESRCH; <--- FAIL } ESRCH is returned all the way to user space, which triggers the glibc test case assert. Returning ESRCH unconditionally is wrong here because the user space value has been changed by the exiting task to 0xC0000000, i.e. the FUTEX_OWNER_DIED bit is set and the futex PID value has been cleared. This is a valid state and the kernel has to handle it, i.e. taking the futex. Cure it by rereading the user space value when PF_EXITING and PF_EXITPIDONE is set in the task which 'owns' the futex. If the value has changed, let the kernel retry the operation, which includes all regular sanity checks and correctly handles the FUTEX_OWNER_DIED case. If it hasn't changed, then return ESRCH as there is no way to distinguish this case from malfunctioning user space. This happens when the exiting task did not have a robust list, the robust list was corrupted or the user space value in the futex was simply bogus. Reported-by: Stefan Liebler <stli(a)linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Acked-by: Peter Zijlstra <peterz(a)infradead.org> Cc: Heiko Carstens <heiko.carstens(a)de.ibm.com> Cc: Darren Hart <dvhart(a)infradead.org> Cc: Ingo Molnar <mingo(a)kernel.org> Cc: Sasha Levin <sashal(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=200467 Link: https://lkml.kernel.org/r/20181210152311.986181245@linutronix.de diff --git a/kernel/futex.c b/kernel/futex.c index f423f9b6577e..5cc8083a4c89 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1148,11 +1148,65 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval, return ret; } +static int handle_exit_race(u32 __user *uaddr, u32 uval, + struct task_struct *tsk) +{ + u32 uval2; + + /* + * If PF_EXITPIDONE is not yet set, then try again. + */ + if (tsk && !(tsk->flags & PF_EXITPIDONE)) + return -EAGAIN; + + /* + * Reread the user space value to handle the following situation: + * + * CPU0 CPU1 + * + * sys_exit() sys_futex() + * do_exit() futex_lock_pi() + * futex_lock_pi_atomic() + * exit_signals(tsk) No waiters: + * tsk->flags |= PF_EXITING; *uaddr == 0x00000PID + * mm_release(tsk) Set waiter bit + * exit_robust_list(tsk) { *uaddr = 0x80000PID; + * Set owner died attach_to_pi_owner() { + * *uaddr = 0xC0000000; tsk = get_task(PID); + * } if (!tsk->flags & PF_EXITING) { + * ... attach(); + * tsk->flags |= PF_EXITPIDONE; } else { + * if (!(tsk->flags & PF_EXITPIDONE)) + * return -EAGAIN; + * return -ESRCH; <--- FAIL + * } + * + * Returning ESRCH unconditionally is wrong here because the + * user space value has been changed by the exiting task. + * + * The same logic applies to the case where the exiting task is + * already gone. + */ + if (get_futex_value_locked(&uval2, uaddr)) + return -EFAULT; + + /* If the user space value has changed, try again. */ + if (uval2 != uval) + return -EAGAIN; + + /* + * The exiting task did not have a robust list, the robust list was + * corrupted or the user space value in *uaddr is simply bogus. + * Give up and tell user space. + */ + return -ESRCH; +} + /* * Lookup the task for the TID provided from user space and attach to * it after doing proper sanity checks. */ -static int attach_to_pi_owner(u32 uval, union futex_key *key, +static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key, struct futex_pi_state **ps) { pid_t pid = uval & FUTEX_TID_MASK; @@ -1162,12 +1216,15 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key, /* * We are the first waiter - try to look up the real owner and attach * the new pi_state to it, but bail out when TID = 0 [1] + * + * The !pid check is paranoid. None of the call sites should end up + * with pid == 0, but better safe than sorry. Let the caller retry */ if (!pid) - return -ESRCH; + return -EAGAIN; p = find_get_task_by_vpid(pid); if (!p) - return -ESRCH; + return handle_exit_race(uaddr, uval, NULL); if (unlikely(p->flags & PF_KTHREAD)) { put_task_struct(p); @@ -1187,7 +1244,7 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key, * set, we know that the task has finished the * cleanup: */ - int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; + int ret = handle_exit_race(uaddr, uval, p); raw_spin_unlock_irq(&p->pi_lock); put_task_struct(p); @@ -1244,7 +1301,7 @@ static int lookup_pi_state(u32 __user *uaddr, u32 uval, * We are the first waiter - try to look up the owner based on * @uval and attach to it. */ - return attach_to_pi_owner(uval, key, ps); + return attach_to_pi_owner(uaddr, uval, key, ps); } static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval) @@ -1352,7 +1409,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, * attach to the owner. If that fails, no harm done, we only * set the FUTEX_WAITERS bit in the user space variable. */ - return attach_to_pi_owner(uval, key, ps); + return attach_to_pi_owner(uaddr, newval, key, ps); } /**

7 years

FAILED: patch "[PATCH] futex: Cure exit race" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From da791a667536bf8322042e38ca85d55a78d3c273 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx(a)linutronix.de> Date: Mon, 10 Dec 2018 14:35:14 +0100 Subject: [PATCH] futex: Cure exit race Stefan reported, that the glibc tst-robustpi4 test case fails occasionally. That case creates the following race between sys_exit() and sys_futex_lock_pi(): CPU0 CPU1 sys_exit() sys_futex() do_exit() futex_lock_pi() exit_signals(tsk) No waiters: tsk->flags |= PF_EXITING; *uaddr == 0x00000PID mm_release(tsk) Set waiter bit exit_robust_list(tsk) { *uaddr = 0x80000PID; Set owner died attach_to_pi_owner() { *uaddr = 0xC0000000; tsk = get_task(PID); } if (!tsk->flags & PF_EXITING) { ... attach(); tsk->flags |= PF_EXITPIDONE; } else { if (!(tsk->flags & PF_EXITPIDONE)) return -EAGAIN; return -ESRCH; <--- FAIL } ESRCH is returned all the way to user space, which triggers the glibc test case assert. Returning ESRCH unconditionally is wrong here because the user space value has been changed by the exiting task to 0xC0000000, i.e. the FUTEX_OWNER_DIED bit is set and the futex PID value has been cleared. This is a valid state and the kernel has to handle it, i.e. taking the futex. Cure it by rereading the user space value when PF_EXITING and PF_EXITPIDONE is set in the task which 'owns' the futex. If the value has changed, let the kernel retry the operation, which includes all regular sanity checks and correctly handles the FUTEX_OWNER_DIED case. If it hasn't changed, then return ESRCH as there is no way to distinguish this case from malfunctioning user space. This happens when the exiting task did not have a robust list, the robust list was corrupted or the user space value in the futex was simply bogus. Reported-by: Stefan Liebler <stli(a)linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Acked-by: Peter Zijlstra <peterz(a)infradead.org> Cc: Heiko Carstens <heiko.carstens(a)de.ibm.com> Cc: Darren Hart <dvhart(a)infradead.org> Cc: Ingo Molnar <mingo(a)kernel.org> Cc: Sasha Levin <sashal(a)kernel.org> Cc: stable(a)vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=200467 Link: https://lkml.kernel.org/r/20181210152311.986181245@linutronix.de diff --git a/kernel/futex.c b/kernel/futex.c index f423f9b6577e..5cc8083a4c89 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1148,11 +1148,65 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval, return ret; } +static int handle_exit_race(u32 __user *uaddr, u32 uval, + struct task_struct *tsk) +{ + u32 uval2; + + /* + * If PF_EXITPIDONE is not yet set, then try again. + */ + if (tsk && !(tsk->flags & PF_EXITPIDONE)) + return -EAGAIN; + + /* + * Reread the user space value to handle the following situation: + * + * CPU0 CPU1 + * + * sys_exit() sys_futex() + * do_exit() futex_lock_pi() + * futex_lock_pi_atomic() + * exit_signals(tsk) No waiters: + * tsk->flags |= PF_EXITING; *uaddr == 0x00000PID + * mm_release(tsk) Set waiter bit + * exit_robust_list(tsk) { *uaddr = 0x80000PID; + * Set owner died attach_to_pi_owner() { + * *uaddr = 0xC0000000; tsk = get_task(PID); + * } if (!tsk->flags & PF_EXITING) { + * ... attach(); + * tsk->flags |= PF_EXITPIDONE; } else { + * if (!(tsk->flags & PF_EXITPIDONE)) + * return -EAGAIN; + * return -ESRCH; <--- FAIL + * } + * + * Returning ESRCH unconditionally is wrong here because the + * user space value has been changed by the exiting task. + * + * The same logic applies to the case where the exiting task is + * already gone. + */ + if (get_futex_value_locked(&uval2, uaddr)) + return -EFAULT; + + /* If the user space value has changed, try again. */ + if (uval2 != uval) + return -EAGAIN; + + /* + * The exiting task did not have a robust list, the robust list was + * corrupted or the user space value in *uaddr is simply bogus. + * Give up and tell user space. + */ + return -ESRCH; +} + /* * Lookup the task for the TID provided from user space and attach to * it after doing proper sanity checks. */ -static int attach_to_pi_owner(u32 uval, union futex_key *key, +static int attach_to_pi_owner(u32 __user *uaddr, u32 uval, union futex_key *key, struct futex_pi_state **ps) { pid_t pid = uval & FUTEX_TID_MASK; @@ -1162,12 +1216,15 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key, /* * We are the first waiter - try to look up the real owner and attach * the new pi_state to it, but bail out when TID = 0 [1] + * + * The !pid check is paranoid. None of the call sites should end up + * with pid == 0, but better safe than sorry. Let the caller retry */ if (!pid) - return -ESRCH; + return -EAGAIN; p = find_get_task_by_vpid(pid); if (!p) - return -ESRCH; + return handle_exit_race(uaddr, uval, NULL); if (unlikely(p->flags & PF_KTHREAD)) { put_task_struct(p); @@ -1187,7 +1244,7 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key, * set, we know that the task has finished the * cleanup: */ - int ret = (p->flags & PF_EXITPIDONE) ? -ESRCH : -EAGAIN; + int ret = handle_exit_race(uaddr, uval, p); raw_spin_unlock_irq(&p->pi_lock); put_task_struct(p); @@ -1244,7 +1301,7 @@ static int lookup_pi_state(u32 __user *uaddr, u32 uval, * We are the first waiter - try to look up the owner based on * @uval and attach to it. */ - return attach_to_pi_owner(uval, key, ps); + return attach_to_pi_owner(uaddr, uval, key, ps); } static int lock_pi_update_atomic(u32 __user *uaddr, u32 uval, u32 newval) @@ -1352,7 +1409,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, * attach to the owner. If that fails, no harm done, we only * set the FUTEX_WAITERS bit in the user space variable. */ - return attach_to_pi_owner(uval, key, ps); + return attach_to_pi_owner(uaddr, newval, key, ps); } /**

7 years

FAILED: patch "[PATCH] ubifs: Handle re-linking of inodes correctly while recovery" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e58725d51fa8da9133f3f1c54170aa2e43056b91 Mon Sep 17 00:00:00 2001 From: Richard Weinberger <richard(a)nod.at> Date: Wed, 7 Nov 2018 23:04:43 +0100 Subject: [PATCH] ubifs: Handle re-linking of inodes correctly while recovery MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit UBIFS's recovery code strictly assumes that a deleted inode will never come back, therefore it removes all data which belongs to that inode as soon it faces an inode with link count 0 in the replay list. Before O_TMPFILE this assumption was perfectly fine. With O_TMPFILE it can lead to data loss upon a power-cut. Consider a journal with entries like: 0: inode X (nlink = 0) /* O_TMPFILE was created */ 1: data for inode X /* Someone writes to the temp file */ 2: inode X (nlink = 0) /* inode was changed, xattr, chmod, … */ 3: inode X (nlink = 1) /* inode was re-linked via linkat() */ Upon replay of entry #2 UBIFS will drop all data that belongs to inode X, this will lead to an empty file after mounting. As solution for this problem, scan the replay list for a re-link entry before dropping data. Fixes: 474b93704f32 ("ubifs: Implement O_TMPFILE") Cc: stable(a)vger.kernel.org Cc: Russell Senior <russell(a)personaltelco.net> Cc: Rafał Miłecki <zajec5(a)gmail.com> Reported-by: Russell Senior <russell(a)personaltelco.net> Reported-by: Rafał Miłecki <zajec5(a)gmail.com> Tested-by: Rafał Miłecki <rafal(a)milecki.pl> Signed-off-by: Richard Weinberger <richard(a)nod.at> diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c index a08c5b7030ea..0a0e65c07c6d 100644 --- a/fs/ubifs/replay.c +++ b/fs/ubifs/replay.c @@ -212,6 +212,38 @@ static int trun_remove_range(struct ubifs_info *c, struct replay_entry *r) return ubifs_tnc_remove_range(c, &min_key, &max_key); } +/** + * inode_still_linked - check whether inode in question will be re-linked. + * @c: UBIFS file-system description object + * @rino: replay entry to test + * + * O_TMPFILE files can be re-linked, this means link count goes from 0 to 1. + * This case needs special care, otherwise all references to the inode will + * be removed upon the first replay entry of an inode with link count 0 + * is found. + */ +static bool inode_still_linked(struct ubifs_info *c, struct replay_entry *rino) +{ + struct replay_entry *r; + + ubifs_assert(c, rino->deletion); + ubifs_assert(c, key_type(c, &rino->key) == UBIFS_INO_KEY); + + /* + * Find the most recent entry for the inode behind @rino and check + * whether it is a deletion. + */ + list_for_each_entry_reverse(r, &c->replay_list, list) { + ubifs_assert(c, r->sqnum >= rino->sqnum); + if (key_inum(c, &r->key) == key_inum(c, &rino->key)) + return r->deletion == 0; + + } + + ubifs_assert(c, 0); + return false; +} + /** * apply_replay_entry - apply a replay entry to the TNC. * @c: UBIFS file-system description object @@ -239,6 +271,11 @@ static int apply_replay_entry(struct ubifs_info *c, struct replay_entry *r) { ino_t inum = key_inum(c, &r->key); + if (inode_still_linked(c, r)) { + err = 0; + break; + } + err = ubifs_tnc_remove_ino(c, inum); break; }

7 years

FAILED: patch "[PATCH] ubifs: Handle re-linking of inodes correctly while recovery" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

7 years

[PATCH] memcg, oom: notify on oom killer invocation from the charge path

by Michal Hocko

From: Michal Hocko <mhocko(a)suse.com> Burt Holzman has noticed that memcg v1 doesn't notify about OOM events via eventfd anymore. The reason is that 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path") has moved the oom handling back to the charge path. While doing so the notification was left behind in mem_cgroup_oom_synchronize. Fix the issue by replicating the oom hierarchy locking and the notification. Reported-by: Burt Holzman <burt(a)fnal.gov> Fixes: 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path") Cc: stable # 4.19+ Acked-by: Johannes Weiner <hannes(a)cmpxchg.org> Signed-off-by: Michal Hocko <mhocko(a)suse.com> --- Hi Andrew, I forgot to CC you on the patch sent as a reply to the original bug report [1] so I am reposting with Ack from Johannes. Burt has confirmed this is resolving the regression for him [2]. 4.20 is out but I have marked the patch for stable so it should hit both 4.19 and 4.20. [1] http://lkml.kernel.org/r/20181221153302.GB6410@dhcp22.suse.cz [2] http://lkml.kernel.org/r/96D4815C-420F-41B7-B1E9-A741E7523596@services.fnal… mm/memcontrol.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 6e1469b80cb7..7e6bf74ddb1e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1666,6 +1666,9 @@ enum oom_status { static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order) { + enum oom_status ret; + bool locked; + if (order > PAGE_ALLOC_COSTLY_ORDER) return OOM_SKIPPED; @@ -1700,10 +1703,23 @@ static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int return OOM_ASYNC; } + mem_cgroup_mark_under_oom(memcg); + + locked = mem_cgroup_oom_trylock(memcg); + + if (locked) + mem_cgroup_oom_notify(memcg); + + mem_cgroup_unmark_under_oom(memcg); if (mem_cgroup_out_of_memory(memcg, mask, order)) - return OOM_SUCCESS; + ret = OOM_SUCCESS; + else + ret = OOM_FAILED; - return OOM_FAILED; + if (locked) + mem_cgroup_oom_unlock(memcg); + + return ret; } /** -- 2.19.2

7 years

[PATCH 0/1] f2fs: fix sanity_check_raw_super on big endian machines

by Martin Blumenstingl

Big endian machines (at least the one I have access to) cannot mount f2fs filesystems anymore. This is with Linux 4.14.89 but I suspect that 4.9.144 (and later) is affected as well. commit 0cfe75c5b01199 ("f2fs: enhance sanity_check_raw_super() to avoid potential overflows") treats the "block_count" from struct f2fs_super_block as 32-bit little endian value instead of a 64-bit little endian value. I tested this fix on top of Linux 4.14.49 but it seems that all stable and mainline kernel versions are affected: - 4.9.144 and later because 0cfe75c5b01199 was backported there - 4.14.86 and later because 0cfe75c5b01199 was backported there - 4.19 - 4.20-rcX Martin Blumenstingl (1): f2fs: fix validation of the block count in sanity_check_raw_super fs/f2fs/super.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.20.1

7 years

Re: [BREAKAGE] Since 4.18, kernel sets SB_I_NODEV implicitly on userns mounts, breaking systemd-nspawn

by Thomas Backlund

Den 23-12-2018 kl. 01:28, skrev Linus Torvalds: > On Sat, Dec 22, 2018 at 3:07 PM Christian Brauner > <christian.brauner(a)canonical.com> wrote: >> >> However, for this case should I resend the revert? > > Since I was pointed at the original email thread, I just picked it up > from there directly. It still applied cleanly, nothing had changed in > that area. > > Linus > This should also be picked up for 4.19 lts Greg, it's now upstream as: From 94f82008ce30e2624537d240d64ce718255e0b80 Mon Sep 17 00:00:00 2001 From: Christian Brauner <christian(a)brauner.io> Date: Thu, 5 Jul 2018 17:51:20 +0200 Subject: Revert "vfs: Allow userns root to call mknod on owned filesystems." -- Thomas

7 years

[PATCH] MIPS: math-emu: Write-protect delay slot emulation pages

by Paul Burton

Mapping the delay slot emulation page as both writeable & executable presents a security risk, in that if an exploit can write to & jump into the page then it can be used as an easy way to execute arbitrary code. Prevent this by mapping the page read-only for userland, and using access_process_vm() with the FOLL_FORCE flag to write to it from mips_dsemul(). This will likely be less efficient due to copy_to_user_page() performing cache maintenance on a whole page, rather than a single line as in the previous use of flush_cache_sigtramp(). However this delay slot emulation code ought not to be running in any performance critical paths anyway so this isn't really a problem, and we can probably do better in copy_to_user_page() anyway in future. A major advantage of this approach is that the fix is small & simple to backport to stable kernels. Reported-by: Andy Lutomirski <luto(a)kernel.org> Signed-off-by: Paul Burton <paul.burton(a)mips.com> Fixes: 432c6bacbd0c ("MIPS: Use per-mm page to execute branch delay slot instructions") Cc: stable(a)vger.kernel.org # v4.8+ --- arch/mips/kernel/vdso.c | 4 ++-- arch/mips/math-emu/dsemul.c | 38 +++++++++++++++++++------------------ 2 files changed, 22 insertions(+), 20 deletions(-) diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c index 48a9c6b90e07..9df3ebdc7b0f 100644 --- a/arch/mips/kernel/vdso.c +++ b/arch/mips/kernel/vdso.c @@ -126,8 +126,8 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) /* Map delay slot emulation page */ base = mmap_region(NULL, STACK_TOP, PAGE_SIZE, - VM_READ|VM_WRITE|VM_EXEC| - VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, + VM_READ | VM_EXEC | + VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, 0, NULL); if (IS_ERR_VALUE(base)) { ret = base; diff --git a/arch/mips/math-emu/dsemul.c b/arch/mips/math-emu/dsemul.c index 5450f4d1c920..e2d46cb93ca9 100644 --- a/arch/mips/math-emu/dsemul.c +++ b/arch/mips/math-emu/dsemul.c @@ -214,8 +214,9 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, { int isa16 = get_isa16_mode(regs->cp0_epc); mips_instruction break_math; - struct emuframe __user *fr; - int err, fr_idx; + unsigned long fr_uaddr; + struct emuframe fr; + int fr_idx, ret; /* NOP is easy */ if (ir == 0) @@ -250,27 +251,31 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, fr_idx = alloc_emuframe(); if (fr_idx == BD_EMUFRAME_NONE) return SIGBUS; - fr = &dsemul_page()[fr_idx]; /* Retrieve the appropriately encoded break instruction */ break_math = BREAK_MATH(isa16); /* Write the instructions to the frame */ if (isa16) { - err = __put_user(ir >> 16, - (u16 __user *)(&fr->emul)); - err |= __put_user(ir & 0xffff, - (u16 __user *)((long)(&fr->emul) + 2)); - err |= __put_user(break_math >> 16, - (u16 __user *)(&fr->badinst)); - err |= __put_user(break_math & 0xffff, - (u16 __user *)((long)(&fr->badinst) + 2)); + union mips_instruction _emul = { + .halfword = { ir >> 16, ir } + }; + union mips_instruction _badinst = { + .halfword = { break_math >> 16, break_math } + }; + + fr.emul = _emul.word; + fr.badinst = _badinst.word; } else { - err = __put_user(ir, &fr->emul); - err |= __put_user(break_math, &fr->badinst); + fr.emul = ir; + fr.badinst = break_math; } - if (unlikely(err)) { + /* Write the frame to user memory */ + fr_uaddr = (unsigned long)&dsemul_page()[fr_idx]; + ret = access_process_vm(current, fr_uaddr, &fr, sizeof(fr), + FOLL_FORCE | FOLL_WRITE); + if (unlikely(ret != sizeof(fr))) { MIPS_FPU_EMU_INC_STATS(errors); free_emuframe(fr_idx, current->mm); return SIGBUS; @@ -282,10 +287,7 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, atomic_set(&current->thread.bd_emu_frame, fr_idx); /* Change user register context to execute the frame */ - regs->cp0_epc = (unsigned long)&fr->emul | isa16; - - /* Ensure the icache observes our newly written frame */ - flush_cache_sigtramp((unsigned long)&fr->emul); + regs->cp0_epc = fr_uaddr | isa16; return 0; } -- 2.20.0

7 years

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-stable-mirror