unix: correctly track in-flight fds in sending process user_struct
Fixes a regression caused by the previous partial fix for CVE-2013-4312. Ignore ABI changes as we never build unix sockets as a module and nothing OOT should use the scm functions.
This commit is contained in:
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a47af1b9f9
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5810ec7828
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@ -1,8 +1,13 @@
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linux (4.4.2-4) UNRELEASED; urgency=medium
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linux (4.4.2-4) UNRELEASED; urgency=medium
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[ Roger Shimizu ]
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* [armhf] dts: imx6dlq-wandboard-revb1: use unique model id
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* [armhf] dts: imx6dlq-wandboard-revb1: use unique model id
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(Closes: #813881).
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(Closes: #813881).
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[ Ben Hutchings ]
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* unix: correctly track in-flight fds in sending process user_struct
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(regression in 4.3.3-6)
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-- Roger Shimizu <rogershimizu@gmail.com> Wed, 24 Feb 2016 01:30:38 +0900
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-- Roger Shimizu <rogershimizu@gmail.com> Wed, 24 Feb 2016 01:30:38 +0900
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linux (4.4.2-3) unstable; urgency=medium
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linux (4.4.2-3) unstable; urgency=medium
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@ -1,5 +1,11 @@
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[abi]
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[abi]
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abiname: 1
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abiname: 1
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ignore-changes:
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# Not used by OOT modules
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__scm_destroy
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__scm_send
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scm_detach_fds
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scm_fp_dup
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[base]
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[base]
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arches:
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arches:
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155
debian/patches/bugfix/all/unix-correctly-track-in-flight-fds-in-sending-process-user_struct.patch
vendored
Normal file
155
debian/patches/bugfix/all/unix-correctly-track-in-flight-fds-in-sending-process-user_struct.patch
vendored
Normal file
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@ -0,0 +1,155 @@
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From: Hannes Frederic Sowa <hannes@stressinduktion.org>
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Date: Wed, 3 Feb 2016 02:11:03 +0100
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Subject: unix: correctly track in-flight fds in sending process user_struct
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Origin: https://git.kernel.org/linus/415e3d3e90ce9e18727e8843ae343eda5a58fad6
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The commit referenced in the Fixes tag incorrectly accounted the number
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of in-flight fds over a unix domain socket to the original opener
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of the file-descriptor. This allows another process to arbitrary
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deplete the original file-openers resource limit for the maximum of
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open files. Instead the sending processes and its struct cred should
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be credited.
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To do so, we add a reference counted struct user_struct pointer to the
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scm_fp_list and use it to account for the number of inflight unix fds.
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Fixes: 712f4aad406bb1 ("unix: properly account for FDs passed over unix sockets")
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Reported-by: David Herrmann <dh.herrmann@gmail.com>
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Cc: David Herrmann <dh.herrmann@gmail.com>
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Cc: Willy Tarreau <w@1wt.eu>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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include/net/af_unix.h | 4 ++--
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include/net/scm.h | 1 +
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net/core/scm.c | 7 +++++++
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net/unix/af_unix.c | 4 ++--
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net/unix/garbage.c | 8 ++++----
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5 files changed, 16 insertions(+), 8 deletions(-)
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diff --git a/include/net/af_unix.h b/include/net/af_unix.h
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index 2a91a0561a47..9b4c418bebd8 100644
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--- a/include/net/af_unix.h
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+++ b/include/net/af_unix.h
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@@ -6,8 +6,8 @@
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#include <linux/mutex.h>
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#include <net/sock.h>
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-void unix_inflight(struct file *fp);
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-void unix_notinflight(struct file *fp);
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+void unix_inflight(struct user_struct *user, struct file *fp);
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+void unix_notinflight(struct user_struct *user, struct file *fp);
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void unix_gc(void);
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void wait_for_unix_gc(void);
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struct sock *unix_get_socket(struct file *filp);
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diff --git a/include/net/scm.h b/include/net/scm.h
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index 262532d111f5..59fa93c01d2a 100644
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--- a/include/net/scm.h
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+++ b/include/net/scm.h
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@@ -21,6 +21,7 @@ struct scm_creds {
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struct scm_fp_list {
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short count;
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short max;
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+ struct user_struct *user;
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struct file *fp[SCM_MAX_FD];
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};
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diff --git a/net/core/scm.c b/net/core/scm.c
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index 14596fb37172..2696aefdc148 100644
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--- a/net/core/scm.c
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+++ b/net/core/scm.c
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@@ -87,6 +87,7 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
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*fplp = fpl;
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fpl->count = 0;
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fpl->max = SCM_MAX_FD;
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+ fpl->user = NULL;
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}
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fpp = &fpl->fp[fpl->count];
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@@ -107,6 +108,10 @@ static int scm_fp_copy(struct cmsghdr *cmsg, struct scm_fp_list **fplp)
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*fpp++ = file;
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fpl->count++;
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}
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+
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+ if (!fpl->user)
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+ fpl->user = get_uid(current_user());
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+
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return num;
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}
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@@ -119,6 +124,7 @@ void __scm_destroy(struct scm_cookie *scm)
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scm->fp = NULL;
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for (i=fpl->count-1; i>=0; i--)
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fput(fpl->fp[i]);
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+ free_uid(fpl->user);
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kfree(fpl);
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}
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}
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@@ -336,6 +342,7 @@ struct scm_fp_list *scm_fp_dup(struct scm_fp_list *fpl)
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for (i = 0; i < fpl->count; i++)
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get_file(fpl->fp[i]);
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new_fpl->max = new_fpl->count;
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+ new_fpl->user = get_uid(fpl->user);
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}
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return new_fpl;
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}
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diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
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index 49d5093eb055..29be035f9c65 100644
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--- a/net/unix/af_unix.c
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+++ b/net/unix/af_unix.c
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@@ -1496,7 +1496,7 @@ static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
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UNIXCB(skb).fp = NULL;
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for (i = scm->fp->count-1; i >= 0; i--)
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- unix_notinflight(scm->fp->fp[i]);
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+ unix_notinflight(scm->fp->user, scm->fp->fp[i]);
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}
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static void unix_destruct_scm(struct sk_buff *skb)
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@@ -1561,7 +1561,7 @@ static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
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return -ENOMEM;
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for (i = scm->fp->count - 1; i >= 0; i--)
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- unix_inflight(scm->fp->fp[i]);
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+ unix_inflight(scm->fp->user, scm->fp->fp[i]);
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return max_level;
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}
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diff --git a/net/unix/garbage.c b/net/unix/garbage.c
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index 8fcdc2283af5..6a0d48525fcf 100644
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--- a/net/unix/garbage.c
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+++ b/net/unix/garbage.c
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@@ -116,7 +116,7 @@ struct sock *unix_get_socket(struct file *filp)
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* descriptor if it is for an AF_UNIX socket.
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*/
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-void unix_inflight(struct file *fp)
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+void unix_inflight(struct user_struct *user, struct file *fp)
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{
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struct sock *s = unix_get_socket(fp);
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@@ -133,11 +133,11 @@ void unix_inflight(struct file *fp)
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}
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unix_tot_inflight++;
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}
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- fp->f_cred->user->unix_inflight++;
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+ user->unix_inflight++;
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spin_unlock(&unix_gc_lock);
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}
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-void unix_notinflight(struct file *fp)
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+void unix_notinflight(struct user_struct *user, struct file *fp)
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{
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struct sock *s = unix_get_socket(fp);
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@@ -152,7 +152,7 @@ void unix_notinflight(struct file *fp)
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list_del_init(&u->link);
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unix_tot_inflight--;
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}
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- fp->f_cred->user->unix_inflight--;
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+ user->unix_inflight--;
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spin_unlock(&unix_gc_lock);
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}
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@ -133,3 +133,4 @@ bugfix/all/iff_no_queue-fix-for-drivers-not-calling-ether_setup.patch
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bugfix/arm/net-mv643xx_eth-fix-packet-corruption-with-tso-and-t.patch
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bugfix/arm/net-mv643xx_eth-fix-packet-corruption-with-tso-and-t.patch
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bugfix/x86/x86-efi-bgrt-fix-kernel-panic-when-mapping-bgrt-data.patch
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bugfix/x86/x86-efi-bgrt-fix-kernel-panic-when-mapping-bgrt-data.patch
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bugfix/x86/x86-efi-bgrt-replace-early_memremap-with-memremap.patch
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bugfix/x86/x86-efi-bgrt-replace-early_memremap-with-memremap.patch
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bugfix/all/unix-correctly-track-in-flight-fds-in-sending-process-user_struct.patch
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